Breakdown of haha ha kudamono ga suki desu.

Questions & Answers about haha ha kudamono ga suki desu.
は marks 母 as the topic (“as for mother”), telling us who or what we’re talking about.
が marks 果物 as the grammatical subject of the adjective 好き—in other words, the thing being liked. Since 好き behaves like a な-adjective/noun (“liking”), the thing you like is introduced with が, not with the direct-object particle を.
In Japanese, 好き isn’t a verb that takes a direct object. It’s treated like a な-adjective (“likable”), so the thing someone likes is its subject, marked by が. You’d never say 果物を好きです—the correct pattern is X が 好き(です).
好き is a な-adjective (sometimes called a nominal adjective).
- Predicatively (to state “someone likes something”) you say 好きです for politeness:
母は果物が好きです。 - Modifying a noun (to say “the fruit I like”) you use 好きな:
好きな果物は何ですか。
です is the polite copula that makes the sentence formal. You can switch levels of formality:
- Polite: 母は果物が好きです。
- Plain (written or familiar): 母は果物が好きだ。
- Casual (spoken among friends): 母は果物が好き。
Japanese nouns don’t normally change for singular/plural. 果物 can mean “fruit” or “fruits” depending on context. If you really need to emphasize multiple fruits, you could say 果物たち (rare) or use counters like 果物を三つ (“three fruits”), but usually 果物 alone is fine.
Add the possessor 私の before 母:
私の母は果物が好きです。
You can also use お母さん for “(your/my) mother” in conversation:
お母さんは果物が好きですか。
Replace 私の母 with お母さん (to ask about someone’s mother), keep は/が, and add か at the end:
お母さんは果物が好きですか?