The 3-way O / Infinity Sign / Upside down heart switch controls the polar pattern.
The circle means the omnidirectional polar pattern.
The infinity sign means a figure 8 polar pattern.
The upside down heart is actually a cardioid symbol, and refers to a cardioid polar pattern.
The straight line / hockey stick switch controls the low cut filter. (Off = straight line, On = hockey stick)
The -10db is an attenuation switch. In the 0 position, you'll get stronger electric signals from the microphone. (Attenuation is a weakening of a signal.)
More importantly, here's how you benefit from these switches...
Polar patterns indicate the position where the microphone picks up most of its sound. A cardioid pattern picks up more sound directly in front of the mic. Since the Nady SCM 1000 is a "side address microphone", that actually means the face of the microphone with the logo on it. Everywhere else, you'll get a certain amount of signal rejection. The cardioid pattern is the most useful and intuitive setting because you can use it to emphasize what you're trying to record, and deemphasize all other sounds. For example, if you point it at the sound hole of an acoustic guitar, you'll hear more guitar and less fret noise than if you pointed it at the neck. Pretty simple.
The omnidirectional polar pattern picks up sound equally (almost equally) from all around the microphone. This is used most often when you want to pick up "ambiance," or the natural sound of a room. This is often called a "room mic" for that reason. If you recorded your acoustic guitar up close with another mic, you could use your Nady with the omnidirectional setting to pick up the natural echos and sound reflections of the room. It's a way to get reverb... real reverb.
The figure 8 polar pattern is useful in two ways. If you have two singers, for example, they could face one another and each use one face of the mic. It will pick up both of them equally while rejecting noise coming from the sides. Another use for figure 8 is in mid/side stereo recording. You need a second non-figure-8 microphone to do it. You can Google the technique if you're interested. It's a bit advanced.
The low cut filter is useful for most material. If you're only ever recording acoustic guitar and vocals, always put it in hockey stick position and leave it there. In this position, it will attenuate signals starting at a certain frequency. The lower the frequencies (below that threshold), the more it is attenuated. The "hockey stick" is meant to represent a frequency response graph when the switch is engaged. (See here for an example: http://www.nagraaudio.com/pro/images/information/AudioPrecision.gif)
Low cut is generally a good thing because it attenuates thumps and thuds which you really don't want on your recording. Also, low sounds have a lot more energy in them than do high sounds of equal loudness. So even if an instrument produces low sounds, you may sometimes wish to engage low cut just to take some of it out. You would want the low cut off (straight line) to pick up a lot of low frequencies, such as when you record a bass drum, for example.
The -10db switch, when engaged, reduces gain by 10 db. It takes out some of the signal strength coming out of the mic. It's useful when the source of the sound is very loud because you get finer control over gain on your other equipment. Recording a drum kit is a good example of when you might wish to engage this switch.
Above you have the "ground rules", but mic placement and the use of mic settings is sometimes more an art. It is important to experiment. By doing so, you are learning your equipment and getting the best possible sound.
Good luck with your music.