Ich habe Geld bekommen.
I got money.
Ich habe eine Summe Geld bekommen.
I got a sum of money.
Ich habe eine große Summe Geld bekommen.
I got a large sum of money.
Compare this to
Ich habe Tee getrunken.
I drank tea.
Ich habe eine Tasse Tee getrunken.
I drank a cup of tea.
Ich habe eine große Tasse Tee getrunken.
I drank a big cup of tea.
Here we have a particular thing and a unit of measurement that indicates how much of it there is.
ein Liter Milch = one liter of milk
fünf Meter Stoff = five meters of fabric
eine Prise Salz = a pinch of salt
ein Sack Kartoffeln = a bag of potatoes
This works different than in English. In English, the core of the nominal phrase is the unit, and then you add the information, of what:
What did you buy? I bought a bag. What kind of bag? I bought a bag of potatoes.
In German you think the other way round. The core of the nominal phrase is the thing itself, and then you add an attribute to it which indicates how much of it:
Was hast du gekauft? Ich habe Kartoffeln gekauft. Wieviel davon? Ich habe einen Sack Kartoffeln gekauft.
What did you buy? I bought potatoes. How much of them? I bought a bag of potatoes.
Sometimes you can use this way of thinking and the corresponding construction in English too:
ein Liter Milch = one liter milk
fünf Meter Stoff = five meters fabric
But this construction without of in English is an option in some cases in English, is used almost always in German.
But in German you can use a construction that is similar to the English one, but this is elevated language (gehobene Sprache), not to say pretentious language (überhebliche Sprache). (Heben = to lift; gehoben = lifted, überheben = to over-lift):
Der Graf trank ein Glas des Weines.
The count drank a glass of wine.
Here the phrase des Weines is a genitive attribute of Glas, so it's a construction comparable to the construction in the English sentence. But normally you would say it this way:
Der Graf trank ein Glas Wein.
The count drank a glass of wine.
This genitive-construction sounds less pretentious (but still advanced language) if you want to add some attributes to the wine:
Der Graf trank ein Glas des edlen Weines.
The count drank a glass of the noble wine.
But even in this case we prefer the "normal" construction:
Der Graf trank ein edles Glas Wein.
The prince drank a fine glass of wine.
Note, that grammatically the adjective edel is not an attribute of the noun Wein, but of the noun Glas. But still you don't mean that the count drinks wine from an exquisite glass. You mean that he drinks an exquisite wine, and the amount he drinks is one glass. (So here Glas/glass is not a vessel, but a unit.)