Why is there a strange tint and grain in my film photos?

I’m a complete newbie to photography, and I started out on an old Nikon FM10 that runs on film. I got back my first roll after development and most of them are either over or under exposed. Two of the pictures are given below, and I can’t wrap my head around what is wrong with them. They look really old and have a weird tint and grain to it. Can you take a look at these photos and tell me where I’m going wrong so I don’t repeat the same mistake in the future?