The phrase "feel free" usually means go ahead, as you wish, or it's okay to do so. For example, if a person asks whether he can use another party's phone, the answering person may say, "Feel free." The phrase is an idiom, which means it is an expression that is not interpreted literally but figuratively. Since it isn’t meant to be translated literally, most people use it in casual speech rather than in formal speech or writing.
There are many ways to tell someone it's all right to do something. A person may simply use such words as "okay," "all right," or "yes" to indicate that he has no objections to the particular act. In many cases, however, people choose to answer in ways other than the obvious. In such a case, a person may choose a phrase such as "feel free" rather than simply saying "okay" or "yes." Regardless, the words and phrases generally mean the same thing — the speaker has no objection.
Sometimes examples can make it easier for a person to understand what an idiom is. For instance, if an individual asks a coworker if he can use something on his desk, the coworker might reply with the phrase "feel free." This basically means the coworker who answered has no objection to the asker's request and should go ahead and use it.
Another example of a case in which a person might use this phrase involves a situation in which a person has a problem and would like the sympathetic ear of a friend or colleague who will listen and help him talk it through. In such a case, a willing listener may tell the person to feel free to call on him when he needs someone to talk to. This basically lets the person know he has someone to reach out to when he needs this type of help or attention.
The important thing for a person to remember when he is using idioms is that the person to whom he is speaking may not always understand what he is saying. Usually, a person can depend on the person to whom he is speaking to understand if the listener is also from the same region. This is due to the fact that idioms typically are common to particular areas. If an individual is from a foreign country, he may have a more difficult time understanding idioms.