Is the following sentence a question!?
what should be the meaning of life
I don't mean the meaning I'm talking about Grammer and structure
The initial word "what" and the inverted word order mark this as a question.
What should be the meaning of life?
What should the meaning of life be?
are equivalent in meaning. Either word order is acceptable if the subject is a noun.
If, however, the subject is a pronoun, it is idiomatic for the pronoun to be placed between the modal and main verb.
I have only a rudimentary knowledge of the history of the development of English. I can speculate that this difference between the treatment of noun and pronoun is a holdover from Germanic word order.
Yes, it's a question. Sentences that begin with an interrogative word, like "who", "what", "where", "why", or "how", followed by a form of "to be", are normally questions.
"Who is that man?"
"Where was Waldo?"
"How will you know?"
Etc. "Should be" here is a variant on "to be".