Adverb clauses provide information about other parts of the sentence. They explain why, when, and under which conditions something happens.
These examples help understand their use:
why: I quit my job because I didn’t like the company.
when: Apples are picked after they ripen.
condition: He keeps eating eggs every day even though he knows they’re high in cholesterol.
condition: I will help you if I have time.
Adverb clauses form complex sentences, so you can also reverse the order of the clause–just use a comma (,)
If I have time, I will help you.
After they ripen, apples are picked.