BusinessService.cs

public class BusinessService
{
  private readonly ILogger _logger;
  
  public BusinessService(ILogger logger)
  {
    _logger = logger;
  }
  
  public void SomeMethod()
  {
    _logger.Write("Hello world");
  }
}

var service = new BusinessService(new ConsoleLogger());

ConsoleLogger.cs

public class ConsoleLogger : ILogger
{
  public void Write(string message)
  {
    Console.WriteLine(message);
  }
}

ILogger.cs

public interface ILogger
{
  void Write(string message);
}