Father, or Heavenly Father, is a specific reference to the part of the Godhead who created the universe. The Father is one part of the Godhead, or Trinity, which is comprised of the Father, the Son (Jesus, the Christ), and the Holy Spirit.
The imagery of having a Father in Heaven, loving us, caring for us, watching over us, and protecting us is a comforting thought — for most people.
Unfortunately, some people don’t have a loving, caring, protective biological father, so this imagery is difficult for them to understand or may even produce negative feelings towards God. Those in this situation, shouldn’t assume their Heavenly Father is like their biological father but instead realize their Heavenly Father is perfect, whereas their biological father — like all people — is flawed and makes mistakes.
It is the habit of many to address prayers to our Heavenly Father, but the reality is that we can pray to all persons of the Trinity, either in whole or in part.