The part of speech that connects words or groups of words is called a conjunction.

Explanation:

Conjunctions are words used to link words, phrases, or clauses together, showing the relationship between them.

Examples of conjunctions you provided:

• for
• and
• nor
• but
• or
• yet
• so

These are all coordinating conjunctions , which connect elements of equal grammatical rank (e.g., two nouns, two independent clauses).

Example sentences:

• I want to go to the park, but it is raining.
• She likes coffee and tea.
• You can have cake or ice cream.
• He didn’t study, so he failed the test.

If you want, I can also explain other types of conjunctions like subordinating or correlative conjunctions!