At college level, you will get opportunities from both service based companies and product based companies. If you are focusing on Product Based companies, Data structures and Algorithms should be your main focus. Make sure to complete them by June (considering placements will start from July/August) Solve more and more problems from Geeksforgeeks and Leetcode. You should try to solve at least 15 problems of each data structure and algorithm (arrays, stacks, linked list, queues, binary search, sorting, recursion, dynamic programming, trees, graphs etc.)
Once you are done with around 15 questions for each, you will get the basic confidence to go ahead and solve more complex problems.
Start studying interview experiences of the companies that are coming to your campus for placements. This will give you an extra edge to you over your peers because you would have already practiced the similar kind of questions that the company may ask.

Being a fresher,

If we are aiming for a SDE role :

Firstly, we need to know atleast one programming language thoroughly (C++, python etc.)

First round for shortlisting for any company will be a Technical test which will mainly comprise of coding questions (for which definitely DSA is must). Some companies even ask some aptitude questions where questions related to mathematics/logics are asked. For DSA I would prefer to start with building confidence for each and every topic [like Arrays, Graphs, Trees, Bit manipulation etc].

There are many resources available to help you with that like Interviewbit, Leetcode and Gfg. Once you gain confidence by solving easy-medium level problems of all topics we can start with practicing in timed environment which can be attained by giving online coding contests which generally happen on Leetcode, Codechef , codeforces etc.

This will really boost up your confidence and will prepare you to be ready and think in timed-pressured environments like in an interview or a technical test.

2) Interviews: Companies generally for freshers focus mainly on their knowledge of DSA and Algorithms . They may also ask about basic Computer Science concepts like OOPS, DBMS, Networking etc.

For campus placements, companies focus on candidate who have good fundamental knowledge of Data structures, algorithms, and computer science fundamentals and can use them in practical way. work on improving and practicing more of DS and algorithms and concepts of OOPS, OS, Networks and DBMS. you can use Geeks for geeks and leetcode for practice.