1st appearance of letter/word in Tora indicates its essence

Shalom Rav, I heard a shiur from a rabbi. if i understood properly he said that to know the real concept or essence of a hebrew word in chumash we should try to see where the word was used for the first time and its context in chumash. is there a concept or approach like this ..? and if there is an approach like that can you please suggest me a book or a work done by any rabbi who mentions the source of a particular word where and when being used for the first time in chumash ...i am not a fleuent hebrew speaker so any english book suggestible is good and if no book in english atleast any hebrew language book i would like to know..?

The concept that the first place a letter (!) appears teaches its essence is found in chazal (Breishit Rabba 17, 6) and latter day rabbis like the Bnei Yissaachar (p. 166) and especially R. Tzadok of Lublin often uses this type of study. Problem is, these are relatively difficult sources which you won’t find in English. There’s a reason these books aren’t translated into English, for one should first concentrate on more basics (which are found in English) like Siddur, Tanach, Rashi, basic halacha, basic philosophy and ethics, etc. In general, especially if you’re in Israel, it’s no problem to find a rabbi who has experience with beginners (like at Machon Meir) and can subjectively and personally accompany you and advise you in your learning as you advance.