The Kubota B6000e is the first Kubota tractor model imported into the USA. Besides having a weight of only 900 pounds, it MAY be only 2-WD. After 50 years of use it is unlikely the B6000e is generating 10.5 horsepower; more like 7 - 8 horsepower.
I can only cut grass with it? YES - But not very long grass.
Contemporary subcompact tractors weigh 1,400 to 1,700 pounds. Subcompact tractors are fine for mowing grass and moving light loads around a smooth property in the FEL bucket. You can plow an established garden plot with a subcompact tractor, though most with a choice would prepare a garden with a PTO powered rototiller. Few employ subcompact weight tractors on more than two (2) smooth acres, three smooth acres tops.
As soon as a plow on a (light) subcompact tractor encounters any but the smallest underground root or other obstruction, including hard ground, the tractor will lose traction and stop.
When plowing dirt, tractor capability is a factor of 2-WD or 4-WD and tractor weight.
A 4-WD compact tractor with a bare tractor weight of at least 2,700 pounds will pull a single bottom turning plow through almost any moist soil, including sod which has been first mowed VERY SHORT or previously killed with Roundup/Glycophosphate. Plow will sever tree roots up to 1" if roots are not too concentrated.