when i buy a simulator control-6 or 7 channel for learning , can it be used for flying planes later

welcome nagarajan

you can get a pure  simulator box like this one


or buy a transmitter and a dongle(USB) like this one , use the transmitter (Like this) to fly the model virtually using the dongle or in real using the receiver supplied with a transmitter like the one shown below

they both visually may look the same, however pure trainer box does not have a transmitting module and a it doesn't come with a receiver for obvious reasons

Transmitter


receiver


usb dongle