This pattern is a softer, more conversational way to give advice or suggest a solution. Instead of directly telling someone what to do, you say that doing X would be good. It often carries a nuance of 'why don't you...?' or 'you could just...'.

The verb form is the same as the conditional -ば form, so 行く becomes 行けば, 食べる becomes 食べれば, and する becomes すれば. Then you just add いい. For example, if someone is tired, you might say 休めばいい 'You should rest.'

In everyday speech, the い of いい often becomes dropped, giving ばいい, but both are natural. It's also common to hear ばいいのに to express 'it would be nice if...' but that carries a sense of regret or mild criticism. Stick with ばいい for straightforward suggestions.