Learn Polish: Miło mi! Mam na imię Ewa. - Pleased to meet you! My name is Ewa.

Literally, it translates to "pleasantly to me". Miło is an adverb meaning "pleasantly" or "nice", and mi means "to me". Polish uses this short phrase exactly like English speakers use "nice to meet you".

Could I just say Jestem Ewa instead of Mam na imię Ewa?

Yes, you can say Jestem Ewa ("I am Ewa"). However, Mam na imię Ewa, which literally translates to "I have on name Ewa", is the most natural and common way to introduce your first name in Polish.

Why is the word for "I" missing before Mam?

In Polish, the verb ending tells you who is doing the action. The word Mam already means "I have", so you do not need to add the pronoun ja ("I") unless you want to add special emphasis.

What does the na do in Mam na imię?

It is a preposition needed for this specific idiom. Literally, Mam na imię means "I have on name". As a beginner, it is best to memorize Mam na imię as a single chunk meaning "my name is" rather than translating it word for word.