何（なに／なん）

これは何ですか。

Kore wa nan desu ka.

What is this?

Before です it reads なん, not なに

何を飲みますか。

Nani o nomimasu ka.

What will you have to drink?

Before を it reads なに

何人来ますか。

Nan-nin kimasu ka.

How many people are coming?

Before an n-sound it is なん — counters included