A bit is the fundamental unit of storage in a modern computer; the word bit is derived from the phrase binary digit. Each bit, as this suggests, can have one of two states: 0 and 1.
A block is a group of statements that are considered one logical statement. A block is delimited by the "curly braces", { and }; the first of these symbols starts a block, and the second one ends the block. A block can be used anywhere that a statement can be used, and is treated in exactly the same way as if it were one statement. For example, if a block is the controlled block of a if statement, then all of the statements in the block are executed if the condition in the if is true, and none is executed if the condition in the if is false.
A bool (short for boolean) is a type of variable whose range of values is limited to true or false. This is the most appropriate return type for a function that uses its return value to report whether some condition exists, such as operator <; in that particular case, the return value true indicates that the first argument is less than the second, while false indicates that the first argument is not less than the second.
Brace; see curly braces.
A break statement is a loop control device that interrupts processing of a loop whenever it is executed within the controlled block of a loop control statement. When a break statement is executed, the flow of control passes to the next statement after the end of the controlled block.
A byte is the unit in which data capacities are stated, whether in RAM or on a disk. In modern computers, a byte consists of eight bits.