Hi @Arbabmir,
You can find the definition of the clock source numbers at the 24. Clock Generation Module Chapter.

[page 859, S32G2 Reference Manual, Rev. 8, 02/2024]
The table it refers to is at the 23. Clocking Chapter.

[page 801, S32G2 Reference Manual, Rev. 8, 02/2024]
To see all the clocks sources please refers to this table at the reference manual.