The CPU is a resource on the EOS network that the user must reserve from his EOS account in order to conduct transactions.
The CPU is not enough for a transaction, because the EOS network is experiencing congestion, and transactions now require more CPU resources than you have reserved.
You can make several transactions that do not require a CPU resource (CPU-free) on the bloks.io web resource (stake your EOS to resources, or just make a few transactions).
To do this, you need to install Scatter on your computer (checked for viruses and malware), restore your EOS account in Scatter, and log in to bloks.io.

After in the bloks.io resource itself, you can make CPU-free transactions.

You can also participate in our weekly distribution of 10EOS for CPU resources, which is held in our telegram chat @PaytomatRU - you fill out this Google form, and every evening we delegate CPU resources for 10 EOS per month.