Jacob, who is sent, designates the Christ our Teacher. The stone which he places under his head and which he anoints with oil, signifies the Savior. The ladder which reaches to the heavens is the figure of the Cross. The Lord supported on the ladder is Christ on the Cross
I looked it up and the word in question is Hebrew סֻלָּם / Greek κλῖμαξ / Latin scala ...
The Byzantine tradition identifies Jacob's Ladder with both the Cross, by which the righteous ascend into heaven and the damned descend into Hell, but also with the Mother of God, for she is the link that joins heaven and earth.