How is the modal particle "ja" used? Is it the same as "you know"?
Ich kann ja den Artikel auf Deutsch lesen.
Ich kann den Artikel auf Deutsch lesen, weisst du?
"Ja" as a modal particle
1) In statements, ja appeals for agreement (Your example fits here, I believe)
a) by using ja the speaker insists that what he is saying is correct
b) In contrast to doch as an appeal for agreement, ja implies that the speaker and listener have the same opinion, whereas doch implies that their opinions do not agree
2) In exclamations, ja expresses surprise
doch and ja can be used in this manner to simply express suprise that it's [certain quality], whereas aber and vielleicht express surprise that how/to what extent [certain quality] it is
3) ja intensifies a command: using ja in a command can serve as an implied warning/threat, especially if the ja is stressed
4) ja (sogar) can be a focus particle: in a list of nouns, verbs, or adjectives ja and sometimes ja sogar can be used to emphasize one, similar to "indeed" or "even" in English
5) ja as the affirmative particle
Source: Hammer's German Grammar and Usage 5th ed