What should I invest in long term as someone who knows nothing about investing?

I am a student with about $7000 in my savings account that I don’t use and I figured I could put some of that money towards investing long term. I’m hoping to just slowly grow my money and look back at it after a long while Any suggestions on what I should invest in as someone who knows nothing about stocks? Basically I’m looking for something that is stable and can increase my money. It doesn’t matter how fast it grows. Are there specific apps that are usually recommended to invest with? If I’m using money from my savings account, can I set it so that there is a limit to how much of it goes towards investing?