What do you mean: That's per month data.
Running a node with the default settings will consume 3-400 GB of data.
What is my node? How do I know if it's up for a long time?
Your node is the machine that is running the Bitcoin Core software. Your node is up if the Bitcoin Core software is currently running. It is down if the software is not running. It is up for a long time if the Bitcoin Core software has been running on that machine for a long time.
It sounds as if this was designed for folks with unlimited data.
The entire bitcoin network is designed without any consideration for data usage in mind. Many optimizations are currently being made to reduce data usage, but some things cannot be changed because they are part of the consensus rules.