Sooner or later, you're going to get a huge spreadsheet with way too much data to scan visually.
How do you, ahem, filter out what you don't want to see?
One way is to use the AutoFilter.
AutoFilter Basics
Let's say you've got this spreadsheet of employees.
You'd like to just take a look at those from Montana, or those with a particular number of years of service. Something like that.
Click somewhere in the data, and choose Data > Filter > AutoFilter.
You see arrows by all the headings.
Click on one of the arrows, and choose to view all records containing one of the values, or all records containing the top 10, i.e. the ten most frequently occurring values in that column.
Here are the results for selecting one value for one column.
If you choose another value in another column, then you get rows that have the selected value for BOTH columns.

Here, I get rows for people who are in Montana, AND in Kalispell. Which works out fine since Kalispell is a city in Montana.
However, if I choose to view records for people from Montana, and from Portland (a city in Maine and in Oregon but NOT in Montana), I get nothing.
To go back to viewing all the values, select All from the list.
Then you get to view all the records again, once you've selected All for any columns you restricted.
When you're done and want to get rid of the little arrows, click somewhere in the data, and choose Data > Filter > AutoFilter again. There'll be a checkmark and when you select AutoFilter, it will go away.
There's the data the way it was before you started.
Issues With AutoFilter
Here's where things get a little twitchy. What if you try to turn off the AutoFilter and you have not selected a cell somewhere within the AutoFilter results?
You get this.
When you get this, click OK and click somewhere in the data.
Then choose Data > Filter > AutoFilter again. You won't see the checkmark, but that's OK.
Then choose Data > Filter > AutoFilter yet again. This time you'll see the checkmark.

And then the arrows will disappear and you're back to normal.

I also recommend liberal use of the Undo feature, Ctrl Z or click the Undo icon. You can undo at least 20 and possibly more depending on how your system is set up.
Can You Delete Rows When in the AutoFilter Without Deleting the Intervening Data?
I'm glad you asked. Yes, you can. Here's a demo. Look at the range from row 15, Dan Montbatten, to row 20, Beth Jerlin. They're both from Montana. In between you've got Jon, Marcus, and Kyle.
I'm going to view only people from Montana, which includes Dan and Beth but excludes the three rows between.
Now I'm going to delete Dan and Beth.
And they go away. However, Jon, Marcus, and Kyle are still there.