The Hebrew word כִּי is a conjunction with many different uses. In many ways, it is comparable to the Greek οτι. It often functions as a DMW in which case it will introduce a dependent clause functioning either adverbially or substantivally.
Adverbial:
- It can introduce a causal clause in which case it is translated as “because” (Genesis 3:14).
- It can introduce a result clause in which case it is translated as “that” or “so that” (Genesis 10:10).
- It can introduce a concessive clause in which case it is translated “though” (Micah 7:8).
- It can introduce a temporal clause in which case it is translated “when” (Genesis 27:1).
- It can introduce a conditional clause in which case it is translated as “if” (2 Kings 4:29).
Substantive:
The dependent clause will be performing one of the noun functions. Many times it introduces a content clause; e.g. you will know “that…”; or he commanded “that…”
Along the same lines, it can be used to introduce direct discourse in which case it is translated with quotation marks (Exodus 3:12). cf. the same use for οτι in Greek.
Sometimes כִּי functions as a FANBOYS in which case it will almost always be a strong contrastive (like αλλα in Greek) translated as “but” (Genesis 17:15).
Adapted from Seow p. 331-2.