LST refers to the local sidereal time, which is the right ascension (RA) that is on the meridian at your observing location. Objects with RAs equal to the LST are culminating, appearing at their highest point in the sky for the day. Thus they are well-placed for observation.
Once you have done your SkyAlign, find the LST by looking at the MENU under VIEW TIME-SITE. Here it will be displayed as hours, minutes, and seconds (down to a tenth of a second). It is continuously updated by the mount’s firmware.