Grammar JLPT Level N5 - Lesson 20

や is a particle that has several different roles in Japanese, with the most common being as an adverbial particle. や is used similarly to と as 'and', but rather than listing specific things in a group, it lists 'things like (A)'.
や is always used to group nouns, and simply comes directly after them.

• このスーパーには果物(くだもの)や弁当(べんとう)がある。
  This super market has things like fruit and bento's.
• 飛行機(ひこうき)や船(ふね)は大(おお)きいです。
  Things like planes and ships are big.

To compare how と and や are different, imagine that there is a bowl of fruit. In this bowl there are apples, oranges, and peaches. If と is used to list the apples and oranges, it would give the listener the impression that there are no peaches. This is called an 'exhaustive' list, meaning that all possibilities should be listed. However, if や is used, the listener would know that there are other things in the bowl apart from the apples and oranges. In this way, や is a better choice when you want to say 'and', but don't want to limit the group that you are listing.

• 昨日(きのう)の飲(の)み会(かい)でビールとワインを飲(の)んだ。
  Last night at the party, I drank beer and wine. (Only beer and wine)
• 昨日(きのう)の飲(の)み会(かい)でビールやワインを飲(の)んだ。
  Last night at the party, I drank things like beer and wine. (There were other things, but it was mainly beer and wine)