interrupt-on-change will trigger the interrupt when the assigned pins change from high to low, or vice-versa.
weak pull-up is basically an internal version of adding a pull-up resistor between a pin and +V. the "weak" part refers to it being a very low-current pullup, like using a very high-value resistor. The datasheet would have more detailed info about the specifics if you needed.
a 'port' is a group of I/O pins, containing up to 8 I/O. There are ports A, B, C, etc, depending on how many I/O pins the PIC has. The smaller PICs like the 12F675 just have one port, called "GPIO".
pins set to hi/lo - these are just logic levels. An I/O pin has three usual states - high (output, Vdd), low (output, Vss), and high-impedance (logic input)
output 'latch' has to do with the way the I/O pins are controlled based on the values you put in the associated control registers - someone else can probably provide more insight here.