Mary is the greatest of all the Saints, but she is still a Saint, and is not fundamentally different in nature than any other Saint.
She resides in heaven. Like all Saints, she cannot transcend heaven and be physically present with us except by a miracle of God. You may occasionally see prayers or devotionals that seem to ascribe supernatural properties to Mary (such as dwelling in our hearts or souls), but this is more poetic license than theological doctrine.
However, like all Saints, she is “in communion” with us - she is “aware” of us, and cares for us, and she can “hear” our petitions of prayer, and she can offer prayers on our behalf. Scripture tells us that the prayers of the righteous are particularly effective (James 5:16), so we believe that Mary’s prayers pack a pretty good wallop.