Answers:
S- Serif
a - counter
p(1) - bowl
p(2) - descender
l - ascender
The letter 'S' actually comes with a spine and a beak, however; the line is pointed at the serif of the letter. The serif of a letter is the extra accent given the type of typography.
The middle area of the letter 'a' is called a counter, a counter is actually the open space of a closed area in a letter. The counter is often found inside a bowl of a letter.
The curved of the letter 'p' the encloses the letter is called the bowl. The bowl is anything that encloses an area of a letter, but there are some exceptions to the letter 'C' being an open bowl.
The lower area of the letter 'p' that extends below the baseline of the letter is called a descender. The descender is also often called "extender" or "tail loop" on letters that have area below the baseline.
The top area of the letter 'l" is called an ascender. The ascender is the area that extends above the x-height of lower case letters. Some of the letter with ascenders are h, l, b, and k. These letters have ascenders that reach the ascender line of the typography.