Meaning of see and be seen
So "to see" is the action of looking at something, to see something happening or just to see anything, etc.
"See" is a verb. So you use it when you look at something or want someone to see something;
Ex: "I see myself in front of the mirror"
Ex: "Can you see me from there?"
Ex: "See, that's what I told you about!"
To be seen means that someone looks at something, sees something.
"I've seen myself in front of the mirror for over 2 hours"
"Have you seen me from there?"
You can also make it as a passive voice.
Active voice: "Ann saw John near that tree last night"
Passive voice: "John was seen by Ann near that tree last night"
Another example: Active voice: "That man saw the murderer"
Passive voice: "The murderer was seen by that man"
See is a verb, sees is the present tense of this verb and seen is the past tense of the verb. Hope this helps.
I see blue sky. = Blue sky is seen (by me). Do you see the logic? The second sentence is in passive, and the usage of passive/active depends on what you want to emphasize. (Though, it is not a good example as "I see" usually means "I understand", and "I can see" means "I have a visual picture".)
But it works that way: Subject active verb object. ----> Object passive verb (by/with)subject.
Passive forms are made : be + -ed/3rd form of irregular verb .
You can saw see in a conversation. Like I can see you. But you never say you can be seen in a conversation. It is usually found in an advertisement. For celebrities or important people attending events. For example: Lady Gaga can be seen at Wal-mart this weekend shopping for a new pair of underwear.