Translation:Nice to meet you.
If you are on the app you can click the symbol and it gives you a definition. What I do is write the symbol and pronunciation on one side of a flash card then the definition on the other, that way once you've seen it once you can study then do it without having to click it after some practice.
The subject is not always the first word in the sentence, but it always comes before the main verb of the sentence. In this case, the main verb is 很 (in this sentence, it works like the verb "is"). The main part of the sentence is 我很高兴, "I am happy." The first part "认识你" means "to meet you" or "meeting you". It describes the second part. The sentence literally translated would say something like "Meeting you I am happy." As you can see, the subject ("I"/我）comes before the main verb ("is"/很) even though there is another verb in the sentence. In a case like this, it may be best simply to learn the phrase as a set phrase since the Chinese does not translate literally to English.