Very: rất before the adjective

Rất means "very", and it goes before the adjective: rất ngon (very tasty), rất nóng (very hot). It also goes before words for feelings: rất thích (really like), rất nhớ (really miss). As with any adjective, there's no là: Phở ở đây rất ngon.

Rất is the neutral choice and fits everywhere, in writing as well as speech. In relaxed conversation people often prefer lắm after the adjective (ngon lắm), which means the same and sounds warmer, or quá after it (ngon quá!) when they're reacting to something in the moment. In speech you'll also hear rất là ngon, which is a touch more emphatic.

There are two places where rất doesn't go: right after không, and inside a có … không? question. For "not very", put lắm at the end: Món này không cay lắm. To ask "Is it very spicy?", say Có cay lắm không?

One set phrase with rất you'll use from the first day: Rất vui được gặp anh, nice to meet you.