A square has sides of equal length and 4 points where the edges meet. A cube is similar to a square but exists in 3 dimensions, it has 8 points where its edges meet. Mathematically there is no reason why you can't extend this pattern to higher dimensions as a simple formula will tell you the relationship between the dimensions of the object and the number of points (where the edges meet), the formula for the number of points is 2 to the power n where n is the dimension of the object.
The square is 2D and has 2 to the power 2 points (that's 4 points). A cube is a 3D square and has 2 to the power 3 points (that's 8 points). Make a cube out of paper and unfold it to make it 2D again, you can make the shape of a cross out of the paper.
A hypercube exists in higher dimensions, in 4D it will have 2 to the power 4 points. "Unfold" it and you get a shape in 3D called a tesseract.
The painting below by Salvador Dali has Christ crucified on a tesseract. It is a very, very clever painting.
Here is Christ crucified till the ends of the Earth, outside the simple time and place of Calvary 2000 or so years ago. There are no nails and no wounds, but there is pain, look at His hands. Forget about those who literally crucified Christ, He forgave them from the cross for they knew not what they were doing. Christ's pain, in this depiction, is in His heart, it is for our sins that separate us from Him. Our sins, here and now.
We must act. See how the Virgin at his fees raises herself above the 2D chessboard of ordinary reality buy her total devotion to Christ. We must do the same and prepare to plunge ourselves into the depths of His Passion.
Dali could never depict the Passion, not even the nail wounds in Christ's flesh. I like that honesty, and to me it demonstrates a very human and God fearing side to this most exuberant and deliberately enigmatic of artists.