This is presumably the first of the NOTAMs related these works;
29th July 23:00 to 16th Aug 06:00, SUN-THU 2300-0600 Taxiway Alpha closed between A8 and A14 due to work in progress. Backtracks and alternative taxi routes may be required
Source;
https://pilotweb.nas.faa.gov/PilotWe...trievalByICAOs
For details about where A8 and A14 are, see the Aerodrome Chart on the NATS website;
NATS | AIS - Home
I believe that Taxiways Lima and Mike will also be upgraded but I don't know what the resulting PCNs will be.