Pins are - well, pins. Short stubby things sticking out on the inside of the chainring. They make shifting (up) smoother by hooking on to the chain and lifting it from the smaller chainring towards the bigger chainring.

Ramps are small cutouts/changes to the tooth profile, also designed to help with shifting by making it easier for the chain to transition to the bigger chainring.

They do make shifting smoother, but they aren't critical. Bike will still shift OK w/o them.