Can you please tell me what is the meaning of =+A1*B1 vs =A1*B1

Nothing.
Some users are used to write + in front of formula as a habit of some other programs.

It means the same. When you are typing in a formula then if what you have typed begins with an equals sign or an arithmetic operator, then Excel will recognise it as a formula, rather than as text, so you could type:

+A1*B1

and Excel will then display this in the formula bar as:

=+A1*B1

Hope this helps.

Pete

Thank you guys... you are awesomely quick...