Yes, it is a noun. It can mean the faculty (ability to speak) or a statement or oration read to a group.
There is only one part of speech in a noun--noun.
Noun
The part of speech for "archaeologist" is a noun.
Permission is a noun.
The word speech is a noun.
The part of speech for "touchdown" is a noun.
A noun, specifically a proper noun.
Noun is a noun.
noun
The part of speech for the word diplomacy is a noun.
The word speech is a noun.
The word speech is a noun.