The Mitsubishi MSO-N10-1.7A-200V-AC120V is a contactor with an integral overload relay, combining motor starting and overload protection in a single unit. Rated at 1.7 A and 200 V, with an AC 120 V coil, it's sized for small motor or resistive loads where panel space is tight and you want one device to handle both switching and thermal protection.
The 1.7 A rating sets the continuous current the main contacts can carry under normal load, and the overload relay's thermal element is matched to that value for motor protection. The 200 V rating is the maximum line voltage the contactor is designed to switch. The AC 120 V coil voltage means the solenoid that pulls the contacts in is designed for a 120 VAC control circuit — common in North American panel builds where control transformers step down to 120 V. Verify your control voltage matches; a coil rated for AC 120 V will not pull in reliably on 24 VDC or 240 VAC.