Can some body help me understand some parts of a schematic circuit?
The part at the top is a 2-point terminal block.



The part at the bottom is a barrel jack with switch. 



Both are very common parts, but there are many, many different types that would the same schematic symbol. They are just connectors- the first for wires to board (contacts on a relay), the second from something like a wall plug power supply (to the on-board regulator).