I'm glad that I know English when I am talking to foreigners.
I'm glad that I understand English when I am speaking with foreigners.
「外国人」→「Foreigner」
「（誰かと）話してるとき」→「When I am talking/speaking to (someone)」
「～ててよかった」→「Glad that I ~」
まとめて言いますと、
「I'm glad that I know English when I am talking to foreigners.」
「I'm glad that I understand English when I am speaking with foreigners.」
と表現します。
I am glad that I know English. It means I can communicate with more people from around the world.
When I speak to foreigners it makes me happy that I began learning English.
Glad' is another word that we use for happy. Usually it is used when talking about a past action, for example "I am glad I got to see Michael Jackson live before he died."
Obviously when foreigners visit Japan the main language they will use to communicate will most probably be English, so as a person learning English you can communicate with more people, whether they are from the UK, Brazil, France, South Africa or anywhere.
glad'とは、happy（うれしい）と同じ意味の言葉です。たいてい過去に起こったことについて話すときに使われます。
例：
"I am glad I got to see Michael Jackson live before he died."
（マイケルジャクソンが亡くなる前にライブを見に行けてよかった）
外国人が日本を訪れた場合、コミュニケーションをとるのに使う言語はおそらく英語となるでしょう。ですから、英語を学んでいると、より多くの人とコミュニケーションがとれます。それが、イギリス人であれ、ブラジル人であれ、フランス人であれ、南アフリカ人であれ。
I'm glad I studied English so I can talk to people abroad.
Studying English really helps me to talk to people abroad.
Sometimes when you travel to a different country, you may feel nervous if they speak another language. That's why it can be very useful to study the language before you travel so you have more confidence.
A few ways you can mention this fact are:
1) I'm glad I studied English so I can talk to people abroad.
2) Studying English really helps me to talk to people abroad.
海外を旅行をしている時など、外国の人が他の言語で話しかけてくると緊張しますよね。
なので、旅行へ行く前にその国の言葉を勉強すると、自信をもって旅をすることができます。
以下、これについて表す言い方です：
1) I'm glad I studied English so I can talk to people abroad.
（海外の人と話が出来るので、英語を勉強していてよかったです）
2) Studying English really helps me to talk to people abroad.
（英語の勉強は海外の人と話をするのに役立っています）
I feel glad that I studied English when I talk to people from abroad.
I'm extremely happy that I studied English when I am abroad as the people understand me.
These statements show a delight in being able to learn English and that it is very useful when one has traveled abroad.
you can replace the word happy with delighted and the sentence will still make perfect sense.
Speaking to foreigners in English gives me a great sense of satisfaction
I am very proud of the fact that I can hold a conversation in English with foreigners.
It is not necessary to say that you studied English. From the context, this is obvious. It is the fact that that you are glad to speak English which you wish to communicate, and why you are glad is more precisely because you are proud of having achieved something (through diligent study, obviously) and this gives you a sense of satisfaction.
「英語を勉強した」と言う必要はありません。文脈からそれは明らかです。伝えるべきは、英語を話せてうれしく思うということです。なぜうれしく思うのか、より正確には、一つのことを（努力して）成し遂げることができてそれを誇りに思い（I am proud）、充実感（sense of satisfaction）を感じるからです。
When I can hold a conversation with a foreigner, it makes me happy that I studied English.
"To hold a conversation" means that you are able to both understand and contribute to an exchange of thoughts and ideas. A "foreigner" is someone who is from a different country. I hope that this helps. :)
"To hold a conversation"は、会話が成り立つという意味です。
"Foreigner"は、他の国の出身の人を指します。
お役に立てると幸いです。
シンガポール 
イギリス 
アメリカ合衆国 
