In Spanish, a verb with "se" can be used as a more natural form of passive, called "pasiva refleja" (reflexive passive?).
That is the case here "véase" is a form of "verse", that is the "pasiva refleja" equivalent to "ser visto".
According to the conjugation, it is the third person, singular of the present tense of subjunctive. As you probably know the present tense of subjunctive is used sometimes as imperative. In this case it works as a third person imperative (the real imperative only has the second person).
To sum up, "véase" is a reflexed passive third person imperative of the verb "ver".
Maybe it could be translated more literally as "to be seen", but I don't think it work too well.
In Spanish, this kind of passive-imperative was somewhat common when giving instructions, particularly when they are written. "Véase", "nótese", "obsérvese"...
I think it is to avoid the direct imperative, that may be seen as impolite. But now it may be seen as old fashioned, and in modern writings it is repaced with the more informal plural first of the present of indicative. For example in cooking recipes:
Córtese la carne... Caliéntese el agua...
Cortamos la carne... Calentamos el agua...
But this will not work with "véase". You cannot say "vemos página 3"!
