...
I haven't covered functions - eg simple excel functions like IF and CONCATENATE and they are really basic - exactly like excel but different syntax (TIP: Case is important!). See the article about functions below.
Microsoft have created a whole new language for functions - the M Language - See the official formulas reference https://support.office.com/en-us/article/Power-Query-formula-categories-125024ec-873c-47b9-bdfd-b437f8716819
Then there is another whole area of coded functions that I haven't even looked into yet.
...