John Gill Commentary Psalms 78:14

"In the day-time also he led them with a cloud, And all the night with a light of fire." — Psalms 78:14 (ASV)

In the daytime also he led them with a cloud
Which was in the form of a pillar, and went before them, and the Lord in it, and directed their way, and protected them from heat; see (Exodus 13:21Exodus 13:22) (Nehemiah 9:12Nehemiah 9:19).

This was typical of Christ, who is a shadow and security from the heat of a fiery law, the flaming sword of justice, the wrath of God, which is poured forth like fire, the fiery darts of Satan, and from hurt by any enemy whatever; see (Isaiah 4:5Isaiah 4:6) (25:4) , and who leads his people through the wilderness of this world by his Spirit, by his word, and by his own example; and who is the best and safest guide to follow.

and all the night with a light of fire ;
which also was in the form of a pillar, and went before them, and gave light in the night, and the Lord was in it; and this also was typical of Christ, who is the light of his people amidst all their darkness in this world.