Only mortal sins need to be confessed in number. If it is a mortal sin (grave matter, full knowledge, and deliberate consent) then tell the priest how many times you lied. If it is habit, and you don’t know how many times you have lied, at least tell the priest that you have lied many times. If he needs more information, he will ask.
Again, it all depends on the serious nature of the lie, and whether you knew what you were doing at the time and if you were acting in free will or not.
Even if it is not a mortal sin, it will do you good to confess the lie to the priest.