When you figure out which channels are the least crowded and switch to one of those you'll see the immediate difference in your WiFi performance.
Why can it be rather useful to know which channel a wireless network operates on? Because in a WiFi crowded space, where every neighbor has their own network, overlapping channels is the most common reason of a slower connection. You should be able to see which channels networks use, the signal strengths, WiFi encryption methods used, etc.
So what are those WiFi analyzer apps and how does one use them? A WiFi analyzer app detects all available WiFi networks around and should provide you with detailed info on every network it found.