What is the meaning of this information provided by Air Traffic Control? Air traffic controllers seem to broadcast this information, is anyone able to tell me what this is or what its use is for?

LTBA 162120Z 03008KT 360V080 9999 BKN035 06/02 Q1028 NOSIG


Especially the last part, what does NOSIG mean?
This is a METAR, a weather report. From the Wikipedia article:


  METAR is a format for reporting weather information. A METAR weather
  report is predominantly used by pilots in fulfillment of a part of a
  pre-flight weather briefing, and by meteorologists, who use aggregated
  METAR information to assist in weather forecasting.


The meaning of this METAR is:

Location: LTBA
Day of month: 16
Time: 21:20 UTC
Wind:  True direction = 030 degrees, Speed: 8 knots
Wind direction is variable between 360 and 080
Visibility: 10 km or more
Clouds: Broken sky , at 3500 feet above aerodrome level
Temperature: 06 degrees Celsius
Dewpoint: 02 degrees Celsius
QNH (Sea-level pressure): 1028 hPa
No significant changes expected in the near future


NOSIG means: No significant changes expected in the near future.

See this METAR-TAF decoder.