Lifeboats are a thing, so it is a noun.
The part of speech for this particular word is a noun.
part of speech
there was 12 lifeboats.
16 lifeboats 16 lifeboats plus 4 collapsibles
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
No, Titanic had twenty lifeboats.
No, there were only 20 lifeboats.
Were are the lifeboats kept when not in use?
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.