Once you get to the point in your foreign language studies where you are able to start having frequent conversations, you’ll probably start to notice times where the person you are speaking with has difficulty understanding what you are saying.
Rather than say “I don’t understand you”, they may be more indirect and try and play along, in which case you can try and pick up on when their responses don’t seem to quite match what you expect. Or you may not discover this until later, when that person says “Oh, I thought you meant ….”, for example when there was some misunderstanding about an agreement or plan made.
Assuming you are talking with a native speaker of that language, these sorts of things usually indicate that you have made mistakes in your speech, either in terms of incorrect grammar or misuse of certain words.
If you try to actively spot these miscommunications and trace them to their source, often you’ll discover something that can improve your communication ability in that language.
You can use this technique even when conveying your message properly took longer time than expected, in terms of the amount of back-and-forth. In such cases, you can think about what you could have said to communicate more efficiently, with less words. This is especially relevant in Japanese, since words are often omitted more than in English, although if you omit a critical word you can negatively impact the listener’s chance to understand your point.
If you are on good terms with the person you were speaking with, you can ask them whether you misused a certain word or used awkward grammar. If not, you can try to remember the conversation and ask a teacher or friend later about what might have gone wrong.