Grade.

In year 1.
I got a pass in one unit and two distinctions in two other units. What would my overall grade be.

The fact that you say you're in "year 1" suggests that this is a two-year qualification. You say you have "a pass in one unit and two distinctions in two other units" suggests that year 1 contains at least three units. That's all we know about your qualification.
Is it a BTEC? If so, which one? Is it a Pearson BTEC Level 3 National Diploma (equivalent in size to two A Levels)? Or is it perhaps a Pearson BTEC Level 3 National Extended Diploma (equivalent in size to three A Levels). In either case, what it the subject? Or perhaps it's a one-year BTEC like the Pearson BTEC Level 3 National Extended Certificate or the Pearson BTEC Level 3 National Foundation Diploma?
Or perhaps its not a BTEC at all?

It is a two year course of level 3 extended diploma of btec applied scince. I had two distinctions in two units and one pass

Thanks. A BTEC Level 3 National Extended Diploma in Applied Science contains 13 units, typically with 6 units in the first year and 7 units in the second year.
As as result, your first year grade can't be established based upon the grades from just three units.