There are more than fifty verses in the Bible which specifically speak of interpreting something. And there are many things for which an interpretation is needed, such as words (Jn. 1:41), languages (Ezra 4:7), dreams (Dan. 2:5), proverbs (Prov. 1:6), parables (Matt. 13:18), names (Jn. 1:42), the weather (Matt. 16:3), and even the Scriptures themselves (Acts 8:29-39). But the only time the subject of interpretation seems to be controversial is with the "interpretation of tongues." The Apostle Paul addressed spiritual gifts in his letter to the Church at Corinth, where "interpretation of tongues" is included (1 Cor. 12:10; 14:26, 28).
"Tongue," from the Greek word γλῶσσα (glōssa) refers to the tongue as an organ of speech, or to a language/dialect. That definition works fine if one is speaking of the event in Acts 2, where the 120 disciples were filled with the Holy Spirit, and "there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance" (v. 3-4). In that case, Jews from many other nations heard them speak in their own languages (v. 5-11). Obviously, no interpreter was necessary because the hearers understood what was being said.
The problem lies in the fact that Paul must have been speaking of another manifestation of tongues in addressing the Corinthians (ch. 12, 14). There, he is talking about the purpose and use of the spiritual gift of tongues which was to be used to edify the brethren (12:7). He said that speaking in tongues (without an interpreter present) edifies only the speaker (14:4). Since the purpose of the spiritual gift is to build up the members of the assembly (14:5, 12, 26), Paul directed those who had the gift, to speak only when an interpreter was present (14:28). It appears that the gift of tongues was given to be a sign to unbelievers, especially Jews who attended their services (1:22; 14:22).
Bible translators, attempting to help the reader understand what Paul meant by "tongues," inserted the word "unknown" before it (14:2, 4, 13-14, 19, 27). As if that wasn't confusing enough, preachers "help us" by explaining that "unknown" really means a language with which the speaker is unfamiliar. The Church is edified by witnessing the miraculous manifestation and hearing the interpretation in their own language; the lost are provided with a "sign" from God and also by hearing the interpretation. It is my belief that the combination of the two gifts is equal to the gift of prophecy (14:5).
Another need for interpretation occurs when a biblical writer uses a word that is not common to his reader's culture. There are many examples such as an explanation of a person's name (Acts 13:8), a place (Mk. 15:22), a title (Heb. 7:2), etc. Generally, one can tell who the writer was addressing by the words for which he includes a translation. For instance, someone writing to the Jews would not need to interpret a Hebrew word, while one writing the same thing to a Gentile audience would. That is what puzzles me about John's Gospel; to whom is it addressed? He interprets a Greek word in one verse (Messias - 1:41), and in another, a Hebrew (Aramaic) word in the very next verse (Cephas). Oh well, things like that keep me humble.