A database is a collection of data in a structure. It may contain data about many different types of things. For example there is a sample database with world information which you will soon use. It contains data about countries, their cities and the languages spoken.
Each of those three things are called tables (or entities). The country table looks like this:
It contains rows. Each row (or record) is about a thing. Here the first row is about a country called Aruba. The second row is also about a country but a different one.
Each row contains the same information such as the country name or population. Those items are normally referred to as fields or columns.
When you create a table you will define the fields you want. Then you will add rows of data. Then you will use that data.
A database may have many tables. Each table may have many rows of data in fields. The tables may be related to each other (like the countries and their cities) but may also be nothing to do with each other.
Many people will refer to a program as a database (for example Microsoft Access). However the program which does the work for you is properly called a database management system (DBMS). For Web pages one of the most commonly used is MySQL although that is moving to MariaDB.