I am learning German, very slowly though and when I typed red it came up as "rot" in Google translator. Then I typed a red apple and it came up as "ein roter Apfel". The only part I don't get is why it added a -er to the end of it?
Ok, first, every noun is capitalized.
Ein roter apfel
is wrong. It should be
ein roter Apfel.
That said, the
-er is added to the adjective rot (i.e. the adjective rot is declined) according to rules for indefinite articles (starke Deklination).
In your case, your combination
indefinite article + adjective + noun is in nominative, and Apfel is masculine.
Notice that you can translate a red apple as ein roter Apfel if that combination appears in nominative:
Ein roter Apfel wird weggeschmissen.
But it would be wrong to translate a red apple as ein roter Apfel if you eat it:
Ich esse ein roter Apfel. (total falsch! [i.e. plain wrong
It should read:
Ich esse einen roten Apfel.
This answer contains the information you need. To understand it, it might be helpful to you to have precisely the table you need (the table in that answer is for schwache Deklination, but the procedure is the is the same, once you have a table.)
You can't just map German vocabulary onto English syntax and grammar. The basic rule of learning a foreign language is not to think in terms of your native language.
German has its own rules of grammar, and one of those rules will modify some adjectives (such as rot) prior to their objects (i.e. Apfel). A structured course of instruction should help you learn this and other rules that do not directly map onto English.
Adding the -er is called inflection.
Of the various aspects of basic German grammar, I found adjective declension one of the hardest to get a grip on. I recommend that you use a well-designed German course, and don't worry about it too much until after you already understand gender and case. However, here's some more detailed information in case you are curious.
German attributive adjectives decline (i.e. change endings) depending on three things:
- the gender (masculine, feminine or neuter) and number (singular or plural) of the noun they describe
- the case (nominative, accusative, dative or genitive) of the noun phrase that they are a part of
- the declension of the noun phrase, which depends on the case and whether they are preceded by a definite, indefinite, or no article.
Gender All German singular nouns have a property called gender: masculine, feminine, or neuter. Note that this is not necessarily related to the sex of the person or animal the noun refers to. For each noun you must learn its gender.
Case Each German noun phrase has one of four cases, depending on its role in the sentence. The subject is always in the nominative case; the object may be any of the four, depending on the verb, but usually accusative; noun phrases which follow prepositions and show the place where something takes place are in the dative case; and so on.
Declension There are two declensions: weak and strong. Which one to use depends on whether the article gives a "primary case ending": if it does, use the weak, otherwise use the strong declension. Definite articles always provide a primary case ending. Indefinite articles provide primary case endings for some gender/case combinations. If there is no article, the strong declension is used.
An attributive adjective is one that directly modifies the noun (like "ein roter Apfel") rather than through a verb ("Der Apfel ist rot"). Predicative adjectives (the latter) don't decline in German.
the apple is red -- der Apfel ist rot
the red apple -- der rote Apfel
Give you which apple?
The red ONE - Den Roten.
Der rote Apfel wurde gegeben.
Give you which rose?
The red ONE- Die Rote.
Die rote Rose wurde gegeben.
So German has additional information inside the word red. Namely if it is masculin or feminin or neutrum.
Without a grammar in bookform - a grammar for beginners - you won't crack the problem of the two adjective declensions in German. Today the adjectives in English have no endings, but German adjectives have a lot of endings. Curiously Old English had the same system as German adjectives today. But English has abandoned all endings, whereas German still has them. And you have to understand why German has two sets of endings. It is no good learning such declension tables by heart, one has to understand the system. And not every grammar can explain this.
In German the gender, case and number are show by article-words or the adjective. "ein" has dropped the ending -er/es, so the adjective gets the ending -er/es.