Equation

rho is usually density and B is usually magnetism, capital Pi is usually pressure. The upside down triangle is called "del" and it's a differential operator. So you're looking at a magnetic field and whatever "u" is, evolving over time with some constraints on the spatial variation of the field? But none of the symbols are defined. If you ask your nephew what the equations describe, you can keyword and describe the photo so that interested people can find it.