I am a learner, nor a native speaker, but I believe it means 'love is not thought, love is". "Pensa" is a verb in the present tense. Using se with it means it is in the passive voice, so it changes from "thinks" to "is thought". Pensa-se o amor = "Love is thought" . In the negative, the se has to come before the verb instead of after = 'Não se pensa" I guess this is a line from a poem, is it? It seems like a poetic way of speaking. A more familiar phrase might be "Fala-se inglês" (English is spoken here) or in the negative "Não se fala inglês". (English is not spoken here) I hope that is helpful in some way. I am pretty sure I am right but if a Portuguese speaker comes along and tells me I'm wrong then I guess we will both learn something! :^)

There's no way to explain or to understand love. Love is just love.

Yes, 18ck is correct, the translation of this line is "love is not thought, love is". By this, the author means that love is a feeling that can't be thought, analyzed nor planned by reason, it just happens, it just exists and is there, acting in our lives, whether we want it or not, whether we plan it or not, whether we can define it or not. Just one more observation: "love is not thought" can be translated either as "o amor não é pensado" or "o amor não se pensa", those are the two forms of passive voice in Portuguese. The first way is what we call 'voz passiva analítica', the second, we call 'voz passiva sintética', it's just a matter of structure. Because there's only one form in English, they're both translated as "love is not thought". 18ck is correct.

In this case, the author of the phrase meant that "love" is not something to understand, no explanation or how to decipher, "Love" just is. It's like "love" itself explain while it happens. (Sorry if the english is not so good. Hope I helped you)

If I had to translate it, it would be something like "One does not think the love. The love is." It is a way of saying that even if you try, you can't think of a way to define love. "Love is not thought", in Portuguese would be "Amor não é pensado", which doesn't carry the same meaning of the original phrase.