in the following function what does uiTextureLayer stand for ?

void GLBatch::CopyTexCoordData2f(GLfloat *vTexCoords, GLuint uiTextureLayer);

GLBatch is not an OpenGL class (OpenGL has no classes). It is defined by the framework of the OpenGL Superbible version 5. You should look this up in the Superbible’s documentation if you want to know what it does.