Questions & Answers about Het is goed als jij vanavond afwast.
Why is it afwast as one word, rather than wast af?
Afwassen (to wash the dishes) is a separable verb. In a regular sentence, the prefix splits off and goes to the end (like in Jij wast vanavond af). However, because this part of the sentence starts with als (if), it is a subordinate clause. Subordinate clauses push the verb to the very end of the sentence, forcing it to crash back into its prefix and form a single word again: afwast.
Why is the time word vanavond placed before the verb?
Because the word als forces the verb (afwast) into the very last position of the sentence. In Dutch, time words like vanavond (tonight) generally appear early in the sentence (often right after the subject), so it naturally sits in front of the verb at the end.
Why use jij instead of je here?
You can absolutely use je here. Choosing jij just adds emphasis to the pronoun. It heavily stresses "if you wash the dishes tonight" (often implying a contrast, such as "...because I cooked dinner").
Does afwassen just mean "to wash"?
No, afwassen specifically means to wash the dishes or do the washing up. If you are talking about washing your clothes, your hands, or a car, you would use the regular verb wassen instead.