I have a single handle kitchen faucet. The cold water temperature and pressure appears to be fine, however, when I turn the faucet to the hot (left) side, little to no water comes out and it is not hot, not even lukewarm. What could be the issue? Is it the faucet itself? The water heater? Overall, it takes awhile to get warm/hot water from every other faucet/water source...

What kind if water piping do you have in your home? Copper, galvanized, cpvc,

Most likely, you have debris caught in the cartridge and on hot water side. Close water, remove cartridge, flush it under running water, reinstall. See if that helped...