But what does it say? "The word is near you, in your mouth and in your heart" (that is, the word of faith that we proclaim); because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For with the heart one believes and is justified, and with the mouth one confesses and is saved. For the Scripture says, "Everyone who believes in him will not be put to shame." For there is no distinction between Jew and Greek [gentile]; for the same Lord is Lord of all, bestowing his riches on all who call on him. For "everyone who calls on the name of the Lord will be saved."

Note that this verse says one needs to believe in their heart - its not about love from the heart, but rather its faith from the heart. If one repents, that is, the person turns from the current direction towards the saviour, Jesus Christ, putting their faith in something - that something is what is confessed with the mouth. Some get confused here - these two - the belief and the confession are part of the same - one does not exist without the other (else one has faith in faith which is meaningless). One cannot have faith without confession - the confession is the substance of the faith. This has nothing with standing up in a public place and announcing one is putting their faith and trust in Christ - although this is commendable, and indeed, the public aspect of announcement comes with baptism when a saved person demonstrates publically, they have died to the world, and have been risen, new, in Christ. But rather, the whole is a picture; in the same manner we say 'love with all your heart" and here "with the heart one believes". The heart and mouth go together in this picture; Moses wrote - "the word is very near you. It is in your mouth and in your heart, so that you can do it." (Deuteronomy 30:14). Thus, in keeping with the rest of Scripture, it is faith alone that is required for salvation.
It is interesting to note that every single person will to be required to confess Christ as Lord with their tongue (Romans 14:11; Philippians 2:11).