I am wondering if people can get the information of number of foreign languages books and the number of borrowed reader for particularly language from the…

It is possible to find out the number of Vietnamese books from the database of the libraries. In Helmet libraries (Helsinki, Espoo; Vantaa and Kauniainen) there are 1214 books in Vietnamese language, in Vaski libraries 303 and in Piki libraries 212: 

https://haku.helmet.fi/iii/encore/search/C__S%28*%29%20f%3A1%20l%3Avie__Orightresult__U?lang=eng&suite=cobalt

https://piki.verkkokirjasto.fi/en/web/arena/search?p_p_id=searchResult_WAR_arenaportlet&p_p_lifecycle=1&p_p_state=normal&p_r_p_arena_urn%3Aarena_facet_queries=&p_r_p_arena_urn%3Aarena_search_query=mediaClass_index%3Abook+AND+language_index%3Avie&p_r_p_arena_urn%3Aarena_search_type=solr&p_r_p_arena_urn%3Aarena_sort_advice=field%3DRelevance%26direction%3DDescending

https://vaski.finna.fi/Search/Results?sort=relevance&bool0%5B%5D=AND&lookfor0%5B%5D=&type0%5B%5D=AllFields&lookfor0%5B%5D=&type0%5B%5D=AllFields&join=AND&filter%5B%5D=%7Elanguage%3A%22vie%22&filter%5B%5D=%7Eformat%3A%220%2FBook%2F%22&limit=20

There are also other library cooperations which has books in Vietnamese, but these are maybe the biggest. You can see all library cooperations from below. Apart from there are also some libraries outside these library cooperations.

https://fi.wikipedia.org/wiki/Luokka:Suomen_kirjastokimpat

Here below you can see loans of Vietnamese books in the years 2001-2018 in Helsinki City Library:

https://www.avoindata.fi/data/fi/dataset/kirjojen-lainaus-kielittain-helsingin-kaupunginkirjastossa