ScePspFVector3  This struct is used to store 3D vectors. The F in the name suggests that it is a float 3d vector.
Here are the member values:
 float x, the x value of the 3d vector
 float y, the y value of the 3d vector
 float z, the z value of the 3d vector
If you do not know what vectors are you should study the subject. (Study Vectors)
Some might not need floats but need other variable types. For this there are other types:
 ScePspIVector3, Integers
 ScePspSVector3, short integers
 ScePspL64Vector3, SceLong64

ScePspFMatrix4 
This struct is a 4x4 matrix. We use this type
for almost all matrix functions. See also Tutorial
3 about matrices. Here are the 4 member values:
 ScePspFVector4 x, The first row of the matrix in the vector4 form.
 ScePspFVector4 y, The second row of the matrix in the vector4 form.
 ScePspFVector4 z, The third row of the matrix in the vector4 form.
 ScePspFVector4 w, The fourth row of the matrix in the vector4 form.
So with 4 4D vectors we have a 4x4 matrix. This type is aligned. Here are the other types of matrices:
 ScePspFMatrix4Unaligned, the unaligned version.
 ScePspIMatrix4, the integer variant
 ScePspIMatrix4Unaligned, the unaligned integer variant
 ScePspFMatrix3, a 3x3 matrix of floats. Why do we use a matrix
of 4x4 instead of 3x3 when we are in 3D? read (homogeneous
coordinates)
 ScePspIMatrix3, the integer variant of the 3x3 matrix.
 ScePspFMatrix2, the 2x2 float variant.
 ScePspIMatrix2, the 2x2 integer variant.
