I don't understand Genki1's explanation of using の after verbs

Question

Can someone explain? I just don't quite understand it.

Thanks.

Answer 1

Adding "の" immediately after a verb turns the verb into a noun. English does something similar with "-ing."

To swim in Japanese is 泳ぐ.

But if you want to say that you like swimming, 私は泳ぐが好きです does not make sense. That's a bit like saying "I like swim" in English. We want to say "I like swimming/I like to swim."

So you add の after 泳ぐ and now you have 泳ぐの.

泳ぐ = the verb "to swim."

泳ぐの = the noun "swimming."

"I like swimming" in Japanese is "私は泳ぐのが好きです."

Genki also mentions in your screenshot that if the thing you're talking about is already a noun and not a verb, you do not need の. For example, "猫が好きです" is "I like cats."