Presuming you are talking about an internal extractor model High Power with the scalloped 'thumbprint' on the slide... it is difficult to discern any info from just the serial number. If you post photos of each side plus closeups of marks, stamps, serial numbers and anything you find unusual, some here might be able to give a good guess.
Look for a number in a partial box. This will be tiny and poorly stamped and may appear on the front of the trigger guard, the firing pin retaining plate, the foot of your barrel. This will indicate when the part stamped was inspected.
There should also be a letter below and asterisk likely stamped on the left side of the frame and above it on the slide. This is a code for the inspector, Controller of Proof.
There is some meaning for pistols whose serial begins with an E... I will look that up while I await your photos.
In the meantime, your pistol was made probably between 1946 and 1960.
Comments from other forums:
Hi, Anthony Vanderlinden's "FN Browning Pistols" says that the "E" series were pistols that began with an "E" prefix. He says that these we sent to England but not exclusively. Some other numbering prefixes and commercial pistols were also sent. He shows a picture of a "T" series that was sent to England.
If I am reading (Vanderlinden's book) correctly, in the '50s, as serial numbers neared 100,000 an "E" was added as a prefix and did not stand for English or Export. The British contract of the time may have been the first to include these, Germany and Austria also received pistols with the prefix "E".