You shall count: literally “you shall count for yourself.” The two pronouns are singular in form but should be understood collectively as referring to the people of Israel as a whole. In some languages the verb here will be better translated “wait,” as in the similar passage in 15.13.
Seven weeks of years: the word translated weeks is actually translated elsewhere as “sabbaths” and has the root meaning “seven” (see 16.31). So the phrases seven weeks of years (used twice) and “seven times seven years” have exactly the same meaning and can be translated once, if the repetition is stylistically unacceptable in the receptor language.
Quoted with permission from Péter-Contesse, René and Ellington, John. A Handbook on Leviticus. (UBS Helps for Translators). New York: UBS, 1990. For this and other handbooks for translators see here .