"Priming the carb" forces fuel into the carb.

Usually when you attempt to start an engine there is no fuel in the lines, so it will not turn over and start.

You prime the engine by leaving the ignitor OFF and putting your finger over the exhaust ( or intake ) then turning the prop.
You do this a good 3-8 times depending upon the length of your tubing.

It helps to watch the fuel flow into the carb itself the first times you do this ( cowls off ), so you learn what is required.

I find that I must hold my finger over the exhaust through the compression stroke, then release it so the fuel does not get sucked back...
I repeat this as needed.

If the valves close, and your glow plug is glowing, and there is fuel in the head, you should at the least get a few pops.

It sounds like you have not primed your engine enough however.

It may surprise you how much you may need to do this before fuel reaches the carb.

With an electric starter you rarely think of this, as the starter will crank the engine over quickly many times, before it ignites.

If you are hand flipping, then you may have a long way to go before you have enough fuel in the carb.