To “see” God is to know Him, in the direct immediate sense. The Beatific Vision in the next life is the ultimate experience of this knowledge, of this meeting, and is the purpose or goal of man’s existence, And we are to seek it even now, to ‘seek God’s face’ as the Old Testament puts it in several passages; that is our purpose here on earth, to seek after God, and Jesus came to reveal Him as had never been done before.
“When you’ve seen Me you’ve seen the Father”. John 14:9
“Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent.” John 17:3
This is an intimate but still imperfect knowledge in this life, to be fully realized in the next:
“For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known.” 1 Cor 13
None of this knowledge is obtainable by man on his own, beginning with the knowledge that is the object of our faith, which itself is a supernatural gift and a dim foretaste of the fuller knowledge to come according to Aquinas. But some can also be blessed with a fuller taste, a greater “glimpse” of God in this life, for His purposes and only at His discretion. That doesn’t make the person a mystic per se, but it does mean they’ve received a “mystical experience”, aka a “private revelation”. You may or may not have done so but the actual experiences are so ineffably profound that doubt is virtually impossible by the receiver that they’ve been communicated to by a vastly superior Other who’s orchestrated the whole event. It’s simply not the same as a hunch or a dream, etc.