How should I read these climb and descent profile notations?
For the climb profile, the first two values are indicated airspeed -- below 10,000 and above 10,000 feet MSL, and the final value is a Mach fraction. So 250/280/78 would be a climb of 250 knots below 10,000', 280 knots above 10,000', and transition to a climb of Mach .78 somewhere in the high 20's or low 30's (i.e. at the point where 280 KIAS = M 0.78).

For the descent profile, it is the reverse, initial Mach number from Cruise altitude until reaching the transition to indicated airspeed, then the IAS above 10,000', then the IAS below 10,000'.

The 250/280/78 climb profile is very standard for the 737 NG and Max aircraft; most airlines fly them at something fairly close to those speeds, using a Cost Index which starts there and then the FMC applies an adjustment for headwind or tailwind.  In a stiff headwind, the climb speed will increase up to maybe about 310 KIAS (as a ballpark) and Mach .80; with a strong tailwind the speed will go down to maybe 270 and Mach .76 (again, ballpark - exact Cost Index being used affects these adjustments).

The typical descent profile looks similar, although at least in the US we'd never use 280 knots below 10,000' -- it would always be 250 below 10.  If the country you were flying in didn't regulate that, you might do 280 down to close to pattern altitude, but I don't know what countries would allow that, and what you'd gain in time saved (not much) you'd pay for in terms of risk if you hit a big enough bird on or near the windscreen.

But that's what those numbers are almost certainly referring to.