Apico-palatal sounds are also called Retroflex. They are pronounced like the Apico-aveolar except with your tongue curled back a little. Dorso-velar , or just velar, sounds are produced between the back of your tongue and the back of your palate. Glottal simply means your larynx. The categories that form the bold rows refer to the type of articulation.
Stops are sounds that are maintained for a very short amount of time.
You can't stretch no matter how hard you try. On the other hand, Fricatives can persists for forever. Sometimes you can merge stops and fricatives to get Affricates , which starts as a stop and turns into a fricative. Nasals are, well, nasal. They make your sinus vibrates.