Some important capabilities of Salesforce Lightning Connect

• Read from OData - Compliant data sources without APEX. 
• Associate external object records to Salesforce Account records. 
• Write SOQL queries on external object.
• We cannot write into Odata( but possible with apex adopter) and cannot write triggers on external objects(but possible with CDC).
• Instead of copying the data into your org, Salesforce Connect accesses the data on demand and in real time. The data is never stale, and we access only what you need. We recommend that you use Salesforce Connect when:

• You have a large amount of data that you don’t want to copy into your Salesforce org.
• You need small amounts of data at any one time.
• You want real-time access to the latest data.

Even though the data is stored outside your org, Salesforce Connect provides seamless integration with the Lightning Platform. External objects are available to Salesforce tools, such as global search, lookup relationships, record feeds, and the Salesforce app. External objects are also available to Apex, SOSL, SOQL queries, Salesforce APIs, and deployment via the Metadata API, change sets, and packages.