Using the term karma or karmas depends on how purist you want to be with the term. In Sanskrit, the word “karma” is a mass noun, meaning it doesn't have a plural form. It's like “water” or “sand” in English. However, when borrowing the word into English, people often treat it as a countable noun and add “-s”, resulting in “karmas” to indicate different types or individual instances of karma.
So, while “karmas” works in casual English usage, sticking with “karma” as a singular mass noun (without pluralizing it) would be more faithful to its original Sanskrit meaning.
In short: “karmas” is grammatically fine in English, but traditionalists might prefer just “karma.”
Anyway, the next thing I wanna clarify is that the concept of karma is 3 types as standard. Based on some philosophical framework its sometimes considered as 4 types as well. Here's the explanation:
Sanchita Karma
This refers to the vast pool of accumulated karma from all your past lives. It includes every thought, word, and action from previous incarnations. Think of it as the total karmic debt or credit you've built up over many lifetimes.
Prarabdha Karma
From the huge stockpile of Sanchita Karma, a portion is selected to bear fruit in the current life. This is like the “active” karma that shapes your present life circumstances such as your body, family, relationships, life events, etc. Compare it to an arrow that's already been shot; it must reach its target (i.e., be experienced) no matter what.
Agami Karma
The karma you're creating in the present life, while experiencing Prarabdha. This karma will become part of your Sanchita and bear fruit in future lives (mostly). It’s essentially the seeds you're planting now for future outcomes.
These three are the standard that every eastern teaching accepts, yet there is 4th type of karma (optional in some systems)
Kriyamana Karma (Vartamana Karma)
The karma you're creating in the present life that can affect your immediate future rather than being deferred to the next.
Why the Difference?
In Shaivite philosophy, Agami Karma and Kriyamana Karma are grouped together, since they both deal with actions taken in the present life that can affect your present and future lives. Whereas some Vaishnavite philosophies and Buddhist philosophies see Kriyamana as a distinct karma that has an immediate impact on the present life only.
This nuanced distinction is why some traditions list only 3 types of karma, while others prefer the 4-part division.