Can a guy with hypospadias?sexually function properly?

Difficult: Could still have an erection but difficult to deliver sperm if you want to have a child.

Many variables: If the degree of curvature(chordee) is minimal and the urethral opening is near the tip of the penis(glans), sexual function and fertility can be essentially normal. If the opening is closer to the scrotum and the curvature is greater than 30 degrees, intercourse can be painful and difficult if not impossible. Fertility may be compromised if the opening is not far enough toward the tip.

Usually yes: Provided penis is straight or only minimally curved. Significant curvature (chordee) makes insertion & sex difficult if not impossible and needs to be corrected.