The `qrcode` function is a function provided by the qrcode-generator library that generates a QR code. It takes two parameters: the first parameter is the error correction level, which can be 0, 1, 2, or 3, with 0 being the lowest level of error correction and 3 being the highest; the second parameter is the encoding mode, which can be one of four modes: Numeric, Alphanumeric, Byte, or Kanji.

After calling `qrcode` function, you can use its methods to add the data to the QR code and to generate the QR code itself using the `make` method.

Here is an example of how to use the `qrcode` function:

```

// Generate a QR code with error correction level 0 and encoding mode Byte

var qr = qrcode(0, 'Byte');

// Add data to the QR code

qr.addData('Hello World!');

// Generate the QR code

qr.make();

// Get the generated QR code data

var qrData = qr.createDataURL();

```

In this example, we first call the `qrcode` function with error correction level 0 and encoding mode Byte. Then we add some data to the QR code using the `addData` method. Finally, we call the `make` method to generate the QR code, and use the `createDataURL` method to get the generated QR code data in a format that can be displayed on a webpage, for example.