你們會推薦那種外地語言？

首先，不論為方便去旅行或幫助搵工，都冇必要學拉丁文，因為世界上已很少人會用拉丁文溝通，除非你想研究聖經或歐洲古籍，懂拉丁文的確很有用。
現時世界上最多人使用的語言是中文，不過只因中國人多，接著的是英文、印地文、西班牙文、俄羅斯文、阿拉伯文，全都超過二億人使用的。不過印地文只在印度流行，所以繼英文後，用得最廣、最難被其他語言取代的都算是西班牙文、俄羅斯文和阿拉伯文了，再加上香港少人會這些語言，學懂會有一定競爭力的。另外，在香港接觸法文和日文的機會也不少，也可考慮。

"英文是世界語言"

WRONG! Try searching for 'Esperanto' on the Net, or even in Wikipedia. You'll quickly be overwhelmed by the massive information provided, I promise :D.

"法文在很多地方亦有其用武之地"

True. A very important thing to note: by learning french, YOUR ENGLISH LEVEL WILL ROCKET SKY-HIGH! If you read a little history about the english language as a whole, you'll find that many deep english vocabularies are actually from french ("cognates"?). OK, examples:

"Mort" - French word for dead. Try relating this with the English word "mortal" and/or "immortal"
"Vendre" - to sell. Compare with "Vending" in "vending machine"
"Apprendre" - to learn. Compare with "Apprentice"
"Mot" - Word. Compare "Motto"

Do you see what I'm seeing? If you do, French is definitely a first choice for a first foreign language.

Another language that would equally be good is Esperanto. Again, search for it in Wikipedia, I don't want to spoil the fun for you in uncovering new knowledge ;).

Hmm, Latin. Frankly speaking, I have little to no experience in that language (except that I know my school has a school motto in Latin - IN LABOURE GAUDIUM). But hold on! I heard that many scientists in the world like to study Latin to some certain extent. Hell, even some constellation names are in Latin, but anyway, I'd say Latin's a good investment if you're in the "scientific path".

英文看似係世界語言，其實只係因為英國殖民地多，很多國家的人都會懂，現時電腦流行，很多英文都會跟從了美式英文了，例如 colour 會寫 color；
隨著各地華人增多，中文已漸漸比英文重要，但中文太多唔同方言，最好懂得講普通話及書寫白話文；
法國人自視為貴族，唔多睇得起英文，當年老師叫我地見到法國人唔好講英文，要講中文，等對方知你唔識法文，主動跟你講英文才好講，若去歐洲及北美地區，法文會較普及；
若是去中南美洲，西班牙文會比法文更流通
至於拉丁文，現只有梵蒂岡使用，曾為義大利及拉丁美洲流行，由於一些學術的詞彙或文章仍有使用拉丁語，通常研究神學或古代學術者才會去學！

in hk, 1) & 2) is most popular language. If you already master in these 2 languages, then you can start learning different language. It actually depends on what kinds of job you want to find. but 3 or 4 is popular in hk because many jap / korean speaking job.
v拉丁文is not popular in hk. if you only for interest, then you can study at
工聯会 ( they offer cheap course, and you can see whether you are really interest in or not)
1) english
2) mandarin
3) japanese
4) korean
5) german
6) french