I've seen this before, and you might want to investigate a return.
This low CPU speed is a common issue with older used systems and may reflect a bum CPU or motherboard, or even incompatibilities with Win 10 power saving, while the memory number is standard, as it correctly displays 6 GB, but right now, Windows currently only needs 2.2 GB of that - nothing to worry about.
I have 16GB installed, with 6.2 GB used, 9.6 GB free, out of 15.8 GB total.
Did the CPU work at the proper speed with the original Windows 7 install? If so, then go back to Win 7 and be happy it works at all.
If not, I remember people posting about this years ago after buying EXX10-level Latitudes from junk resellers and lots of them had very similar CPU speed issues to yours. If you can, get a refund.