what does this do?

[Mariete]

HTC_TyTN_1.18.262.105_ExtROM_SPA.rar

This is a spanish ROM, isn't it?
I've run it and I haven't noticed any change, is it normal? :confused:

[pof]

Mariete: This is an english forum, if you want to contact me in spanish please PM me directly. I took the freedom of editing your post and translating it to english.

Back to your question, this is an Extended ROM taken from a device with spanish ROM on it. It won't change your device language at all. Read the Hermes for Beginners here to understand the difference between a ROM and a Extended ROM:

http://wiki.xda-developers.com/index.php?pagename=Hermes_For_Beginners