How can I open a file with extension fb2?

File is in Russian language

You could do this by downloading the excellent and free Calibre which can be found here

http://calibre-ebook.com/download

This can be used to convert the fb2 to RTF which Linbre Office will load.
The following is a quote from the manual:

"calibre supports the conversion of many input formats to many output formats. It can convert every input format in the following list, to every output format.

Input Formats: CBZ, CBR, CBC, CHM, DJVU, DOCX, EPUB, FB2, HTML, HTMLZ, LIT, LRF, MOBI, ODT, PDF, PRC, PDB, PML, RB, RTF, SNB, TCR, TXT, TXTZ

Output Formats: AZW3, EPUB, FB2, OEB, LIT, LRF, MOBI, HTMLZ, PDB, PML, RB, PDF, RTF, SNB, TCR, TXT, TXTZ"

Hope this is useful

Calibre is more for catalogue management (but of course can read all the formats it can catalogue). The package fbreader is the usual method of reading FB2 files under GNU/Linux.

According to
http://www.fileinfo.com/extension/fb2
I would try to open in Writer or Base.

But it might be necessary to have the extension mentioned in above link.

Writer can be used, although it is not an ideal choice. An FB2 file is simply XML (text) so it can be opened by Writer for editing if necessary. These files are however sometimes zipped (e.g., *.fb2.zip) in which case they will need to be unarchived in order to be edited by Writer (whereas the fbreader package - can read the compressed format natively).