Proper operation of latching relay
The black coil and contacts indicate the contact arrangement for the coil most recently energized, so if you've momentarily connected +5V to pin 6 and 0V to pin 7, you should measure continuity between pins 3 and 4, and between pins 9 and 10.

Then, if you momentarily connect +5V to pin 1 and 0V to pin 12, you should measure continuity between pins 4 and 5 and between pins 8 and 9.

Like this: