Jesus commanded us to love one another. What exactly does that mean?

To love one another, we have to have the mind of Christ. How do we have the mind of Christ?

By thinking and acting like Jesus. How do we think and act like Jesus?

By reading the commandments of Jesus; by meditating on Jesus and what he did/does; by applying Jesus’ values and ideals in our life; by doing unto others as we would have them do to us; by dying to serving sin and living to God; by prayer.

1 Peter 1:22-25 Having purified your souls by your obedience to the truth for a sincere brotherly love, love one another earnestly from a pure heart, (23) since you have been born again, not of perishable seed but of imperishable, through the living and abiding word of God; (24) for “All flesh is like grass and all its glory like the flower of grass. The grass withers, and the flower falls, (25) but the word of the Lord remains forever.” And this word is the good news that was preached to you.

By sincere and devoted service to God, we will bear the fruit of the Spirit.

Gal 5:22-23 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, (23) gentleness, self-control; against such things there is no law.

If we bear the fruit of the Spirit, we will love others. We will put the needs of others before our own needs. We will be kind and compassionate. We will help others in need. We will give to the poor as we are able. We will try and share the wonderful hope of the Gospel message that we have been given. We will not be vengeful, but try and live in harmony with others. We will be humble and not arrogant.

Paul has some very good advice on this subject in Romans 12:9-21:

Let love be genuine. Abhor what is evil; hold fast to what is good. Love one another with brotherly affection. Outdo one another in showing honor. Do not be slothful in zeal, be fervent in spirit, serve the Lord. Rejoice in hope, be patient in tribulation, be constant in prayer. Contribute to the needs of the saints and seek to show hospitality. Bless those who persecute you; bless and do not curse them. Rejoice with those who rejoice, weep with those who weep. Live in harmony with one another. Do not be haughty, but associate with the lowly. Never be wise in your own sight. Repay no one evil for evil, but give thought to do what is honorable in the sight of all. If possible, so far as it depends on you, live peaceably with all. Beloved, never avenge yourselves, but leave it to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.” To the contrary, “if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head.” Do not be overcome by evil, but overcome evil with good.