So I have a joystick wich I have analog signals in from, and I have programmed it so when the joystick is in some locations, digital signal was made. I was has wondering if it was possible to "transfer" those signals so that I can use digital signals like a keyboard to the pc. For an example, when I get a digital high, my pc acts like the button "c" is pressed. I have an arduino uno. Sorry for bad English.
It depends on which USB to TTL serial adapter chip you have on your Uno. The official Uno and faithful clones use the ATmega16U2 chip for this purpose. That is a general purpose microcontroller that can be reprogrammed with a custom firmware that allows you to use your Uno as a keyboard. An example of this and more information is here:
Many of the Uno derivatives use a cheaper application specific chip as the USB to TTL serial adapter. The most common being CH340. These chips can not be reprogrammed. So if your Uno doesn't have an ATmega16U2 then you can't do this.
Even with the right chip on the Uno, this is still a fairly complex project. My recommendation is to get a board that has native USB capability on the primary microcontroller. Examples are the Leonardo, Micro, Pro Micro, MKR boards, Zero, Nano 33 IoT, Due. These boards will be much easier to use as a keyboard because you can just program that into your sketch, rather than having to reprogram a separate chip.
A Leonardo is the exact same size and shape as the Uno. The Micro is my favourite because it is smaller.
For more advanced use of keyboard and joystick, buy a Teensy. They have the native support built in.
Thanks for replying. I have the right chip and found something on the internet wich can help me with this.