The 10 A rating is per contact at the full temperature range; derate if the ambient in your enclosure pushes past 85°C. The 3.96 mm pitch gives enough creepage for the 250 V rating without forcing an oversized board footprint, and the through-hole solder tails (0.146" post length) anchor into plated holes for a mechanically robust joint that survives rework. If your design needs hundreds of mate-unmate cycles, step up to a gold-plated variant in the VH family.
This header mates with the JST VH series receptacle housing (order the matching female connector separately). The receptacle accepts crimp terminals for 18-22 AWG wire, so you can build a custom harness length on site with a standard crimp tool. No special tooling beyond the crimper and a through-hole solder station.