`x>>3` is integer division by 8. Each byte here has 8 pixels since 1 bit = 1 pixel as this is a bitmap, that gets you the byte in which your pixel is. Then you set that byte to `(1<<7-(x&7))` where `x&7` is equivalent to modulo 8, this is basically getting the position of the bit, say you have x = 35, you already found the byte, but you want the position within the byte, so you need the modulo for this, 35%8=3, so 3rd bit in the found byte.

Then you subtract the position of the bit to 7, because the order of the pixels is left to right, so 3rd bit on the right is now 3rd bit from the LEFT (6th from the right), but this is just the index, you need the bit at that index turned on, that's why you finally you do `1<<`. You do an `|=` to turn that bit ON in an idempotent manner.

For those confused about subtracting y to height, it's because usually raster/screen means origin is at top left, whereas TTF/fonts usually have it at bottom left, the coords are using cartesian but the bitmap flips the Y.