9. Likes, needs, having
が: 好き・分かります・あります
The other little sound: が
Some predicates do not act on a thing; they describe how you stand toward it. Liking sushi, understanding Japanese, wanting water, needing a bag. Japanese marks that thing with が instead of を.
私はすしが好きです = "I like sushi" (word for word: as for me, sushi is liked). The person stays the topic with は. The thing takes が. Then the predicate.
The cards that work this way: 好き (like), 嫌い (dislike), 上手 (good at), 欲しい (want a thing), 分かります (understand), できます (can), 要ります (need).
私はすしが好きです。
I like sushi.
日本語が分かります。
(I) understand Japanese.
水が欲しいです。
(I) want water.
英語ができますか?
Can you speak English?
There is / I have: あります・います
あります says a thing exists. います says a person (or animal) exists. The place it exists takes に.
駅にコンビニがあります = there is a convenience store at the station. 東京に友達がいます = I have a friend in Tokyo. With a person as the topic it reads as "have": 私は時間があります, I have time.
Negatives follow the usual ます pattern: ありません, いません.
駅にコンビニがあります。
There is a convenience store at the station.
東京に友達がいます。
My friend is in Tokyo.
時間がありますか?
Do you have time?
お金がありません。
(I) don't have money.
は or が? The beginner rule
は marks what the sentence is about. が marks the thing the predicate is really about. For now: the person is は, the thing is が.
If the thing itself is the topic, use は and skip the person: 袋は要りません, "(as for a bag) not needed", the standard konbini answer.
袋は要りません。
(I) don't need a bag.