What it mean on "Spectrum Analyzer"?

Spectrum Analyzer such as HP E4405B, there's options:

1DN - signal tracking generator

why named "tracking"? what's the difference with common signal generator?

and other option:

1D6 - Time-gated spectrum analysis

why named "Time-gated"? how to comprehend "Time-gated"?

and other option:

1DR - Narrow resolution bandwidths

Is't mean its resolution higher than common spectrum analyzer? but how much is the resolution of common spectrum analyzer?

Thank you everyone!

To my knowlege, time gated analysis, lets u analyse the spectrum between two time instances. In other words, u can analyse the spectrum for any desired time interval alone.

With digital filters inside it is possible to have RBW of 10-100 Hz (SA HP SERIES 70000).

Tracking generator addon is rf generator which signal frequency is in synchronism with observed instantenious frequency of spectrun analyzer. In other words frequency axis of spectrun analyzer and it's tracking generator are in synchronism. Generator tracks spectrum analyser.
With such generator it is possible to sweep transfer function of fourpole circuit etc.

The preceding answer are all exaustive.
I want add a personal comment:
Please take in consideration that the options you mentionated are all high value options!
With that options, the person who choosed them, has trasformed a general purpose S.A. in an High End S.A.
Be confident you have now a very advanced instruments