This is the “passé composé” form of the idiomatic expression “s’en falloir de …”. It is more often used in the “passé composé”. There is no hard and fast translation but instead a plentiful crop of English turns of phrase that can be used, of which you’ll find but a few below.

Usually one finds that verbal form with a complement that in its most general form is “de peu”, “de pas beaucoup”, “d’un rien”, etc. Often enough the complement is more specific and one finds “de quelques secondes”, “de quelques millimètre”, “d’un très petit instant”, etc.

You have the following English translation when the form is used by itself:

Il s’en est fallu de peu! => It was a close thing! or It was a near thing!

When a complement is used other English forms will be more suitable.

Il s’en est fallu de peu que nous manquions le train.
– We very nearly missed our train.

Il s’en est fallu de peu que le chien se fasse écraser.
– The dog was within an ace of being ran over.

Il s’en est fallu de quelques secondes pour que le champion ne batte le record.
– The champion didn’t beat the record but for a few seconds.

Il s’en faut de peu que tu aies rencontré Monsieur Arventier, il vient de partir.
– You just missed Monsieur Arventier, he left a few minutes ago.

Il s’en est fallu de quelques pouces pour qu’elle ne soit pas touchée par la balle.
– It was a matter of inches she wasn’t hit by the bullet. (suggestion by @SteffX question/matter)

Instead of a complement expressing a small amount of time or space “de” can be followed by “beaucoup”.

Il s’en faut de beaucoup pour que la mer atteigne ce point de la plage.
– The sea can’t by any means reach that point of the beach.

Il s’en faut de beaucoup qu’elle soit heureuse.
– She is far from happy.

You can find in Linguee a series of examples of the use of “il s’en est fallu de peu”, all with a translation.

This form is also used in common every day talk, although it is found more often in the idiolect of people with a higher level of education.