Sol or solution/second (Sol/s) refers to the number of hash computations created per second in cryptocurrency mining. Hashes/second (H/s) is usually equivalent to Sol/s but may differ depending on the hashing algorithm used.

• 1 H/s (Hash/second) = 1 Sol/s (Solution/second)

To check for your Sol/s when mining using the default client, you can enter the following to your client -showmetrics flag or add showmetrics=1 to your config and you will be able to see your Sol/s data.
Then you can check your performance against the global hashrate e.g. here https://explorer.zcha.in
To know more about this, I advise you to check out the equihash proof of work given that what we are really talking about here is finding solutions to a mathematical problem but hashrate is what is being used widely for crypto mining.
If I/s or iterations per second which is basically equihash runs per second is used – it should be 2 times the Sol/s rate though. Keep in mind that it is not 20. This is because each equihash run generates approximately 2 solutions. To be honest none other than NiceHash uses this so probably best to ignore.
To summarize, just know that 1 Sol/s = 1 H/s which is being used in Ethereum or Bitcoin mining.