What is your desired rate of return? What is your risk tolerance? How liquid does the investment need to be(do you need to have access to the cash at any time, or can it be tied up for specific periods of time)?
Maybe instead of asking, why not just give some example of the things that where he can invest. Because most of the suggestions here are just the same and popular, trading again and again. And there are a lot of perspective that are coming out that do the same, invest in bitcoin while also investing in real life/properties.
I know of a few different things that someone could invest even with small amounts of money. I will give one example here that I have used over the years called prosper.com. I am not affiliated with Prosper at all other than I have been using them for quite some time. Prosper is a peer to peer lending site the removes banks from the equation. You can choose how much risk you want to accept by using their weighting system for loan risk. If you don't want to take as much risk then only buy AA or A rated loans. If you want bigger returns and are willing to accept more risk then you can venture into the riskier loans. The time frame for repayment is typically 3 years. Loan investments are broken into $25 chunks at a time so that you are not putting too much money in one loan in case of default.
There is also an automated reinvestment process as well if you choose to use it. As your loans get repaid to you the system can automatically reinvest your cash as it hits $25 or more back into the next available loans that meet your criteria. You can get as involved as you want, or you can put it on autopilot and let the system keep reinvesting for you.
It is not without risk. You are hedged by covering a lot of loans with small amounts, but if borrowers default you can still loose money. In the 2007-2008 time frame when the economy tanked I took a beating there for a while. Even people with very good credit ratings and "low risk" loans were defaulting. So this isn't a magic money machine. But since that time and the economy stabilized the rates of return have been pretty consistent with only the occasional loan default. So it has worked out pretty well.
The downside is that your money is tied up for the duration of the loan. So it is not a liquid investment vehicle at this point, but decent rates of return are possible. If you are a risk taker you can get pretty good rates of return if you feel like gambling in loans with people with less desirable credit scores.
If you have any questions about prosper.com I can tell you what I know. I wish I had invested more in prosper over the years, but after I was burned there for a couple of years with the bad loans I really more or less forgot about it and only left a little bit of money in there. That money has continued to grow on autopilot and now looking back I should have just continued to put a little into proper as I went. As long as your time horizon is long enough and you don't need the cash immediately it can be a good investment option.