This the primary tool of the digital marketer,  it is access to Google’s database of search terms where we can research the ‘actual’ search traffic used for a particular keyword plus it will offer alternative keywords.

SEO begins with the use of language and the Keyword Planner permits the marketer to understand language use.

It is free but you  will need a Google account…

https://ads.google.com/aw/keywordplanner/home