- “Crack on” can mean either “start” or “continue”, depending on the context and progress of the activity. 
- British slang meaning to resume an activity and similar to “get cracking” in American slang. 
I think you can do fine all by yourself!
Can somebody explain it please.
- to try to become familiar with someone you would like to date. 
So it sounds like it could mean, “Let’s begin!” or “Let’s continue!” depending one where you are in the process.
For the first one
- Boss is saying to us: ‘Let’s crack on’ – and we start discussing projects.
- Man is discussing with sombody: ‘We’ve cracked on with that girl’
Crack – Commonly used in reference to cocaine.
‘Let’s crack on with. ’ is accepted to mean ‘Make progress’ either by starting or resuming the activity that follows the phrase. eg – let’s crack on with the report means let’s get the report started, or let’s get moving on the report.
Let’s “crack on” What does crack on phrase means. I’ve heared it in following use cases. Boss is saying to us: ‘Let’s crack on’ – and we start discussing projects. Man is discussing