Define parts of speech.

Noun :- The part of speech that is used to name a person,
place, thing, quality, or
action and can function as
the subject or object of a
verb, the object of a
preposition, or an appositive. E.g. 1 Juneid is working.(juneid) subject. 2. Go to school. (school) object to preposition.
3. Asif drowned. (drowned) object to verb.
Pronoun:- The part of speech that substitutes for nouns or
noun phrases and
designates persons or
things asked for,
previously specified, or
understood from the context. E.g. Javid is ill. Javid(noun). He cannot work. He(pronoun) he is used instead of Javid. It is called pronoun.
Adjective:- A word which shows quality of a subject. Or we can say that it adds something to the meaning of noun e.g.
Javid is a good boy. Goodness is a quality of a boy. So the word good is adjective.
Verb:- a part of speech that expresses action, existance, occupance in some languages. Actually it is derived from latin word verbum which means to work. e.g.
Rashid is constructing the building. Word constructing, shows that Rashid is doing some work.