IF condition with binary argument

I am programming a Microchip PIC18F14K50 in C. While checking a code written by another company I stumbled across the following line:

if(MGC_SSPCON2_REG & 0x1F) { // MSSP not idle
...
}

Now, MGC_SSPCON2_REG is implemented as follows

 #define MGC_SSPCON2_REG         SSPCON2

Where SSPCON is the 8bit MSSP Control register (in I2C MODE).

What I do not understand, is how this if-condition works. Is it true when all the bits of the 8bit binary numbers are set to 1? As far as I understand, the argument is the bit wise AND operation on the 8bit register and the binary number 0001 1111 (0x1F).

I hope that I provided enough code to understand the question. I didn`t want to go to much into detail about how the register works.

Thank you in advance for your help :)