When baby is head down, the position of the baby is described by where the occiput, which is the back of the head, is. The usual order of description is the side the occiput is on, then whether it is toward the front side or back. So LOT is left occiput transverse, with the left referring to the mom's left side. A similar system is used when baby is breech, but instead of the occiput, the position is described by the position of the sacrum.
OT (occiput transverse) is a fairly normal position for baby to be in prior to labor. As baby descends through the pelvis, they usually rotate to OA (occiput anterior), but sometimes rotate to OP (occiput posterior.) Very rarely, a baby will not turn from OT, which presents a bigger diameter of the head. Some babies can be born vaginally this way, but some will not descend. This is called "deep transverse arrest." It's rarer than posterior presentation, and certainly can't be diagnosed before labor even starts. Many babies are OT prior to labor and in early labor and rotate just fine in labor. Most likely you have no reason for concern.