How do I search within a single object in salesforce?

Global search is always within easy reach at the top of the page so you can quickly find any searchable object in Salesforce. In Salesforce Classic, you can also use the sidebar search or advanced search.
Know which object you want to search for? In Lightning Experience, select the object in the dropdown list next to the global search box. You can also type the name of the object at the top of the dropdown list. If you don't want to limit your search to a specific object, type your search term in the search box.
As you type, you see suggested records.
Recently accessed items (in Salesforce Classic and Lightning Experience)
Items with matches on the name field (in Lightning Experience only)
Options to limit your search to a specific object (in Lightning Experience only)
We might also apply advanced search features to your search results.
Nicknames—Similar names are returned, like Mike for Michael.
Spell correction—Spell-corrected versions of search terms are returned, like widget for widgte.
Lemmatization—Similar words are returned, like sell, selling, sold.
Expanded query—Records whose name contains the term you entered are returned, like laptop for lap.
Special characters—When your search contains punctuation or special characters, records with similar names are returned, like 1234.SILVER for XYZ-1234-SILVER.
Your admin might have also set up synonym groups, which return records with similar words that have been grouped. For example, USB drive, flash drive, and memory stick.
On the search results page, your most relevant records appear first. The order of results depends several factors, such as how often your search term appears in a record, whether there's an exact match, how unique your search term is, and how much you've interacted with the record. We display only what you have access to.