What each number means
Characters counts every letter, number, space and punctuation mark. Some assignments and forms set a limit without spaces, so both are shown. Sentences are counted at full stops, question marks and exclamation marks, and paragraphs at blank lines.
Reading time assumes about 230 words per minute, which is a typical pace for silent reading. Speaking time assumes 130 words per minute, a comfortable pace for a presentation.
Using the count for a speech
If you have a time limit, the word count is the quickest way to check you are close. Two minutes is roughly 260 words and five minutes roughly 650. The speech timer calculator works it out for a slower or faster pace.
Long sentences are harder to say and harder to follow. If the average is above about 20 words per sentence, try splitting a few before you make your cards. Then paste the speech into the cue card generator or straight into the editor.