"nämlich" is an intensifier (or filler) like "in fact" Se usa como "de hecho". Un saludo, Susanne

"nämlich" is used to express a causal relationship between (main) clauses. It belongs to the conjunctional adverbs by which different types of relationships between clauses are being expressed. Some of them are "zwar", "deshalb", "trotzdem", "andernfalls" and so forth. → "Weihnachten fährt er nach Italien. Er hat dort nämlich Verwandte." (the phrase with "nämlich" tells the reason for what was said in the other one.) The spanish translation is "es que" according to http://esde.dict.cc/?s=n%C3%A4mlich (but I don't know spanish) For conjunctional adverbs see: http://canoo.net/services/OnlineGrammar/Wort/Adverb/Klasse/Konjunktional.html?lang=en

'nämlich' has the same meaning as 'weil' or 'denn', hence it gives the reason for something. The difference is that is is an adverb and it is used more in the spoken language. Er geht nicht spazieren. Es regnet nämlich gerade.. Er geht nicht spazieren, weil es gerade regnet. Er geht nicht spazieren, denn es regnet gerade.