Is there'll a verb or a noun?

Answer 1

The word there'll is a contraction, a shortened form of the pronoun 'there' and the verb (or auxiliary verb) 'will', used to express the future tense of a main verb.
The contraction functions as the subject and verb (or auxiliary verb) of a sentence or a clause.
Note: The word "there" is a pronoun only when it introduces a sentence or a clause. The word "there" also functions as an interjection, an adverb, and a noun. The noun "there" is a word for a place.

Examples:
There will be rain this afternoon.
OR
There'll be rain this afternoon.

I wonder if there will be practice today.
OR
I wonder if there'll be practice today.

Answer 2

"Is" is a verb, while "verb" and "noun" are both nouns.