This equation calculates the bitcoin supply cap

${\sum }_{i=0}^{32}$ : add up whatever's in here, with $i$ going from 0 to 32, i.e. for epochs 0 to 32

$\lfloor \frac{50}{2^i}\rfloor$ : take 50, divide it by $2^i$, then round it down ; this is the block reward per block in epoch $i$

$210,000$ : the total number of blocks per epoch

FYI - the equation is slightly wrong because the floor function should only be used if the units are denominated in satoshis, but in this equation they're denominated in bitcoin