AoA.
I'll try to come up with some simple definitions if you require their meanings in political terminology.
If a party has 51% of the total number of seats in a legislature,then that party is said to have a simple majority in that house.For example American senate has 100 members and if Republican or democratic party has 51 seats in the house they will have a simple majority in the house.
People have different thoughts on this. I think a majority which can not be defeated in a house can be called an absolute majority ie 51%.But some say that a party is said to have an absolute majority if it is able to pass any bill or amendment in the parliament that will be 2/3rd of the total number of seats in the case of Pakistan.
Regards
It means vote by public ie voting in which all can vote irrespective of one's race,caste,creed,gender,education or wealth.The only barrier is the age limit which is varries from country to country ie in Pakistan one can vote if one is 18 or more.
Joint electorates mean elections in which people have to contest and vote irrespective of one's religion, caste etc. The perfect example is available in our History.Muslim league demanded Separate electorates simply because if Muslim contested on general seats they would loose because majority of the population was hindu and they wouldn't vote for a muslim candidate.