Hi Johny, welcome to NST.
The POST (Power On Self Test) routine that initiates as the 1st action before the BIOS setup and the boot sequence, has only one way of communicating with the user because it hasn't got far enough to detect and use the monitor or any other connected peripheral.
It beeps the speaker attached to the mother board.
Count the beeps.
It might be a single number (5 beeps for example) or a sequence of numbers ( 2 beeps followed by 3)
That's the error code which can be looked up with an internet search to find out what is wrong with your hardware.
Most likely candidate would be faulty RAM, but best get the correct error code before making guesses.