Can somebody help me? In the followin sentance, what part of speach is "out".

"The baseball player struck out."

It is a preposition, but it forms part of the verb 'to strike out'.

Verbs comprising more than one word are known as 'multi-word verbs' or 'phrasal verbs'. Other examples are:

To run up a bill.
To run over a cat.

You can see how the preposition (up and over in these examples) changes the meaning of the phrasal verb. Sometimes in phrasal verbs, the preposition is not required.

To heat up the soup.
To heat the soup.

Same deal.

I think

The 'Baseball Player' - > Noun

Stuck out - > Adjective phrase

"To strike out" is a verb phrase, because its head—"strike"—is a verb.