A seer is a person who can see the future, or who has profound insight or knowledge.
A similar word to seer is prophet.
Video: view
A segment is a part of something that can be divided off naturally, without cutting. Oranges and mandarins can be easily broken into segments. You can clearly see the segments of the mandarin in the picture.
Segments can also be used to describe parts of some kinds of a creepy crawly like a millipedes body, where there are clear separations between the parts.
You send something when you make it go somewhere. You send a parcel by taking it to a post office. You send out your troops by ordering them to go.
Sent is the past tense of send. For example, "I sent you a parcel in the post".
Sis forSentence (text)
A sentence is a group of words that make sense on their own, terminated by punctuation.
Sis forSentence (law)
A sentence is something someone has said you must do as a punishment. The woman in the picture has been sentenced to some time in jail.