English "Unified threads" for specifying screw width and thread pitch,
intended for screw sizes under 1/4"

8/32 means unified width #8, which is 0.164" outer thread diameter,
and 32 threads per inch

sizes 12 and 14 are old and uncommon
size 14 is very close to 1/4"

for ((i=0;i<=14;i+=2)) ; do echo "$i: $((60+(i*13)))"; done

0: 60
2: 86
4: 112
6: 138
8: 164
10: 190
12: 216
14: 242

A pitch of 24 is considered coarse and 32 is fine.

Metric sizes are different.  M3.5x0.4 has an outer thread
diameter of 3.5mm and threads are spaced every 0.4mm

Often metric threads omit the pitch as they are either
"fine" or "coarse", and thus may only be marked "M3.5"

In either case, screw length is the measured thread length,
ie the length from bottom of bolt head to tip.