There is no one sign that a man gives to show his love. Each person is unique and expresses love in a personal way. It is best not to pressure a man into demonstrating his love. Men generally reveal their love through their actions and may be more hesitant to do so with words.
Body language reveals a lot. Men who care and love their partners demonstrate this through nonverbal cues. For example, in public, the man may hold your hand or put his arm around you. In private, does the man demonstrate affection spontaneously? Or does he avoid eye contact or keep distance between you? Both are signs of decreased intimacy.
Family and Friends
Perhaps one of the best indicators that a man is really serious about the relationship is if he introduces you to his family and friends. Keep in mind, that if he does not do this, it does not necessarily mean he does not love and care for you. This action must be taken in the context of the man. If he introduces you to friends and family right away, then he is likely a very open person. If this action comes later in the relationship, then it is a serious sign.
When the man discusses his future, are you in it? If the man is serious about the relationship, he is likely thinking ahead and imagining his future with you. If he is not, then his future plans likely will not include you. For example, if he talks about travelling with his friends or working on his career as priorities, you may not be in his future plans. Again, this does not necessarily mean he does not care for you, but it is something of which to take note.
Someone in love is usually affectionate. This affection can be demonstrated in a number of ways. Verbally, physically or very subtly. A man who cares is one who listens and wants to understand you. One who remembers what you like and don't like and is attuned to you. This connection is very subtle but also very strong. Be observant and notice how he demonstrates affection.