China Mobile sent me a short message, but I didn't understand it. Can you explain it to me?

It means that you handled 7 megabytes of traffic this month, and so far, there are 6.51 megabytes left (meaning that you spent nearly 64 megabytes).

At this rate, your traffic may not be enough. I recommend you to apply for a package in 2 yuan (which contains 15 megabytes of traffic). If you do, you will be refunded the phone bill in 2 yuan in the first month.

The rest is what you need to do if you want to handle it.

Note: Generally, just look at this information. If you feel that the traffic is enough, don't pay attention to it, it's just a business promotion.