what is an adjective ?

An adjective is a word used to add something to a noun or to qualify it.
eg: He is an efficient teacher
the word 'efficient' is an adjective in the sentence.

beautiful,rich,neat,clear,easy,difficult etc are some of the adjectives in english

what is a pronoun ?

A pronoun is a word used instead of a noun.
Eg: Mr Babu is a close friend of mine.
He is a clerk.
The first word in the second sentence is a pronoun used instead of the name 'Babu'

some commonly used pronouns.

I,you,we,they,he,she,it,myself,yourself,ourselves,themselves,itself,himself,herself,this,that,one,some,thing,something,someone.somebody,everybody,everything,anybody,anyone,anything,both,either,neither,none,no-one,nobody,these,those.

commonly used prepositions

At,above,about,after,along,for,from,before,because of,due to,in,to,on.onto.up,upon,in spite of,infront of,despite,behind,since,with,without,within,by,than,inside,outside,beside,next to.near,opposite,till,until

what is grammar ?

The rules that say how words change to show different meanings,and how they are combined into sentences.