I can explain with an example perhaps: I am waiting for someone. Some people always keep you waiting. In the first example, ‘someone’ is a placeholder for an unknown or unspecified third person. In the second example, ‘some people’ refers to a category of people who share this characteristic.

也许你想和我聊天，我可以和你的英文帮助下。发我信息，我的微信号：Jirafey

The most important difference is that "someone" is singular (one person), and "some people" is plural (more than one person). "I saw someone outside" means that I saw one person outside. "I saw some people outside" means that I saw more than one person. ("Some" usually means three or more. If I saw exactly two people, I would probably say "I saw a couple of people outside.")

Some one is about one person and you have to use singular verb after that but some people can imply more than one person and you can use singular and plural verb after that.