How do I read this schematic drawing notation for a drill hole?

To expand on comments:

This drawing is a little bit sloppy. As it's a clearance hole, it should just indicate thru diameter and both diameter and depth of cbore. Takes almost no effort in any remotely modern CAD.

When I did some mechanical design, I wouldn't be allowed to do this. Might receive a call from the prototype shop asking me to clarify my intention, might get shot down by the doc control guy in release process.

Most likely interpretation is standard clearance dimensions for #10 screw, as @jko says, but there is ambiguity vs #10 drill per @Jonathan R Swift. By complete coincidence, sizes are similar.

If you can call/email whoever originated the drawing, that might be the way to go.

Rather than a counterbore I suspect that it is a countersink, in which case, I would include the angle. Generally, English hardware uses 82-deg heads whereas Metric uses 90-deg heads. The #10 may just be indicting the English drill size for the through hole, 0.1935-inch diameter (mixing English drill hardware and Metric measurements). If it is a counterbore, then yes, the counterbore depth is missing.