The UVs define what part of a Texture is shown on the Mesh surface. Each face of a Mesh consist of a number of vertices (points) and each of this vertice has (among other attributes) a set of X/Y UV coordinates assigned. UV-Coordinates are floating point and usually range from 0 to 1.
So if you want only a part of the texture to show then you'll enter the UV-Editor of your 3D-Editor (i.e. Blender) and assign the UV-Mappings accordingly.
If you've got a simple plane with a UV-Mapping from 0,0 on one corner to 1,1 to the opposite then you might be able to work with the SpatialMaterials UV1 offset and UV1 scale.
But this is not all. If you place textures of non-adjacent faces next to each other in the texture image then this might provide unwanted results depending on how the texture flags are set. I.e. you might often want to disable "MipMap" as this will interpolate the texture image when it is further away. Because this will tend to let textures "bleed" into each other.