A molecule may be nonpolar either when there is an equal sharing of electrons between the two atoms of a diatomic molecule or because of the symmetrical arrangement of polar bonds in a more complex molecule. For example, boron trifluoride (BF) has a trigonal planar arrangement of three polar bonds at 120°. This results in no overall dipole in the molecule.
Carbon dioxide (CO) has two polar C=O bonds, but the geometry of CO is linear so that the two bond dipole moments cancel and there is no net molecular dipole moment; the molecule is nonpolar.
Examples of household nonpolar compounds include fats, oil, and petrol/gasoline. 
In the methane molecule (CH) the four C−H bonds are arranged tetrahedrally around the carbon atom. Each bond has polarity (though not very strong).  The bonds are arranged symmetrically so there is no overall dipole in the molecule. The diatomic oxygen molecule (O) does not have polarity in the covalent bond because of equal electronegativity, hence there is no polarity in the molecule.