The basic idea is that they are in parallel, however they are possibly located at many different places on the PCB, but not always.
Some schematics will show several capacitors all together in one place, and you don't really know where they are physically located. This is very common on VCC and other power lines. For very complex schematics a designer might do this so that other areas of the schematic don't become overly cluttered by too many parts. On the actual PCB there can be a few capacitors at the power supply entry points, a few scattered around the board, and a few right at chip power pins (as by-pass caps).
There can be a number reasons for the different physical locations. One is because PCB traces are not perfect, they can have small resistances and inductances. You would want to place the caps in locations that work best with those small imperfections.
Placing caps right at the power pins of a chip can reduce noise from getting out of the chip and causing problems further back on the trace, even though the trace might already have a large cap at the opposite end.
Other times you may see a large value cap and a small value in parallel, this may be because the component they filter require special conditions that can only be satisfied by mixing different types of caps. For example a cap with low ESR might not have a high farad value, but you need both, so you would place a large value electrolytic cap in parallel with a small ceramic cap (which often has a low ESR).
On some very high frequency boards you might physically see two small value capacitors at both ends of a short trace. In this case the trace may be purposely used as a small inductor. The schematic for these boards will sometimes shows the caps separated with an inductor, but you won't see a normal inductor on the board.