Traditionally Key Words meant using lots of positive action words in a CV such as “Implemented”, “Created”, “Managed”, “Designed” etc, but this is no longer the case.
These sort of words are still important but only to a human reader.
What does that mean?
It means that your CV will initially be looked at by a search engine of some description. When you apply for a job you will be one of many, and to save time and effort recruiters increasingly use automated screening to search the CVs. The key words they type in will be directly related to the job specification. For instance if they are looking for a programmer with c++ experience then these are the key words they will look for – “programmer” and “c++”. If they’re not on your CV you won’t get past this stage.
Look at your CV and see if it contains the key words that can summarise your experience.