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@yoav
That's a rather old fashioned BB setup. The drive side cup is non-adjustable and screwed all the way in using a large flat sided spanner. The non-drive side cup is adjustable, using a weird tool with pins to engage those holes (or a screwdriver and hammer) and locked into place with the lockring.
Some designs had an adjustable cup with lockrings on both sides.
It needed to be adjustable because the ball bearings were loose inside the cups and you could alter the tension.
On modern solid axle BB with sealed unadjustable bearings, you screw in the whole unit from the drive side and lock it from the non-drive side using a splined tool.