It usually means just that - the journal is interested in your article but is not able or willing to publish it until some changes have been made. The changes requested will be mainly based on the recommendations of peer reviewers, whose identity is usually unknown to you and to whom you are also unknown.
This will vary between journals, but you are not always required to make all the suggested changes to get the article published. Sometimes peer reviewers will have misunderstood your article, or have asked for changes which you are not prepared to make. You may not wish to change your article in a way that you disagree with merely to please the editor or peer reviewer. Usually the important thing is that you engage with the reviews. Sometimes the criticisms they make allow you to identify a problem with your article that the reviewers have not seen. Make the changes which will improve your article, and reply courteously to the editor explaining what you have done and why.
If you are unsure about the changes you need to make to your article to get it published, consult your supervisor, mentor or a more experienced colleague.
If the article is still not accepted and the editor requires you to make further changes which you cannot accept, it may be time to withdraw from that journal and approach another one.