Strokes are the lines that make up characters.
Serifs are the small tails at the end of strokes.
The Baseline is the line on which all character rest. Some character (y, g, p, q) may go below the baseline however the main shape of the letter form still sits on the baseline; these are called descenders.
The Cap is the line where uppercase letters stop. Some lower case character may go above the cap; these are called descenders.
The X-Height is distance between the baseline and the average height of lowercase letters.
The majority of typefaces come with different weights (light, regular, bold, italic) which can be used to together to emphasise or draw attention to parts of text.