A record is a collection of keys and values. You access such values invoking its keys (or labels):
set theRecord to {a:1, b:"string", c:{1, 2, 3}, d:{a:1, b:2}}
tell theRecord
its a --> a number: 1
b of it --> a string: "string"
end tell
c of theRecord --> a list: {1,2,3}
theRecord's d --> a record: {a:1, b:2}
Keys can be also properties defined by developers:
display dialog "Hello!" giving up after 5
--> {button returned:"OK", gave up:false}
Here we get some info after we display a dialog: the button pressed by the user (if any) and if it was gave up.