The following Copy commands are available on the Edit menu:

Edit > Copy

This is the standard "copy" command that copies both native worksheet data to the cyclic GS-Calc copy/paste buffer, plain text to the Clipboard as well as the image/PNG representation of the copied range or objects (e.g. charts).
Subsequent copied native data can be accessed via the menu attached to the Paste button. The copy/paste level can be changed in the Settings > Options dialog box; the default buffer size is 5.
When you paste the copied data you only need to point to the top-left cell of the target location. If you perform any selections, GS-Calc will try do duplicate the copied source data within this selection only:

Edit > Copy Values

Similarly to the above, except that for cells with formulas it copies their values.

Edit > Copy Width Options

In addition to the above you can define all the parameters are typically used for text data/files: separators and fixed column widths, quoting symbol, whether copied data should be formatted, text encoding.
If you need some specific settings for various tasks, you can save them in the displayed dialog box as predefined named sets of parameters selectable with one click.

Edit > Copy As HTML

Copies a range of cells as a HTML code. You can paste that copied Clipboard data directly to any HTML page/data in other applications as one continuous block. The copied HTML data displayed in Web browsers look the same as in the worksheet window, including styles and formatting except for the text rotation. Also, the "accounting" numeric style requires that you use (for the related cells) in GS-Calc some font from the fixed-width font family, like Courier New.

Edit > Copy As Image To

Copies selected data to a jpg/png/gif/bmp/tiff file.

Edit > Copy To PDF

Copies the selection (a range, or object/chart) to a PDF file.

Edit > Copy As Location

Creates and copies (as text) a reference to the current cell/selection and automatically adds it to the list of references that you use in the various Insert > ... formula composers and to the Go To list on the toolbar (that you can use to go to or to select a given range).

Edit > Copy As Worksheet Hyperlink

Creates and copies (as text) a hyperlink to the current cell/selection that is similar to the above "location" copying except it prefixes that text with the hyperlink protocol name and tells GS-Calc to set the "hyperlink" cell format for the cell(s) where you paste that text. Clicking such a hyperlink cell causes jumping (and selecting) the specified cell/range. To move back to that clicked cell, use the toolbar bookmark "Back" button.

Edit > Paste

Pastes the copied data. Copied native data take precedence over the Clipboard data if other program copied its own data.

Edit > Paste without Styles

Pastes the copied data. Copied native data are pasted without styles/formatting.

Edit > Paste As Text

Pastes available data (including numbers and formulas) as text strings.

Edit > Paste with Options

Pastes available text data using definable parameters that are typically used for text data/files: separators and fixed column widths, quoting symbol, escaping symbol, text conversion types, text encoding, saving cell styles detected in formatted numbers in dates.

Edit > Paste Image

If there are any image data copied/available, this command pastes that image.

Edit > Insert Copied Cells

Works similarly to Paste except that columns or rows in the target area are shifted left (columns) or down (rows).