The blue part of the model, in the above diagram, (also Xm) is the magnetizing inductance. It represents the inductance that would separate the real world transformer from an ideal one. If it is a ferrite core with a saturation or hysteresis, the Xm inductor represents that inductance.
The red portion represents the ideal transformer.
We know how to deal with ideal transformers, they are easy, it transfers voltage and current from the primary to the secondary via a ratio of turns. The problem is real world inductors are not ideal, they have leakage inductance, all of the magnetic field does not transfer from the primary to the secondary.
I would imagine that the red portion is what they are talking about when they specify an inductance (but I'd have to see the datasheet)
If there are two numbers, the leakage inductance should be smaller than the transformer inductance by a large amount since I would not expect the leakage inductance to be more than 5% of the total inductance because most transformers have more than a 95% efficiency rating