In Biblical Hebrew, this word is more likely to be translated as “thus” or “so”, when used as an adverb. Throughout B’reisheet (Genesis) one, it is translated: “and it was so”, as in chapter 1:7,9,11,15…
It can also be an adjective meaning “right” “upright” or “honest”, although The First Hebrew Primer doesn’t have this particular definition. It is good to know, since we will run across this as we read the Torah. See Sh’mot (Exodus)10:29 as an example.
כן על, al keyn, is an idiom which includes keyn: meaning = “therefore” an example is B’reisheet 2:24.
כן אחרי, ah’charayee keyn, is another idiom meaning = “afterwards” and an example can be found in B’reisheet 23:19.
Further, keyn as a NOUN means “base, pedestal, stand” as found in Sh’mot (Exodus) 30:18, 30:28, 31:9, 25:16. If you look these up, you will see כנוֹ, with the possessive attached, translate: “its base” (It = masculine).
In Modern Hebrew, keyn means “yes”, but that is a very recent additional meaning. If you are interested in delving into some more etymology and further idiomatic phrases utilizing KEYN, check out this website: