google spreadsheet: join arrays using function NOT CODE

Let's say your arrays are:

A1:A3 = {1;2;3} and B1:B3 = {4;5;6}

Write somewhere: ={A1:A3;B1:B3}

Semicolons ; are used to separate rows, and commas , are for columns.

Here is the documentation: Using arrays in Google Sheets

=FLATTEN(A1:A3,B1:B3) should do the trick

TRANSPOSE() //takes matrix as argument and returns transposed matrix
SPLIT() //breaks apart a string based on a delimiter character (char(13) here)
ARRAYFORMULA() //applies the formula within to array vs cell
CONCATENATE() //joins each cell in each range with a char(13), then the next cell...then the next matrix of cells (to which the first process also happens)
//note char(13) is a carriage return, i will call CR for ease

so if you have matrix A : 1, 2, 3 and matrix B : 4, 5, 6

the steps would look like this:

TRANSPOSE(SPLIT(ARRAYFORMULA(CONCATENATE("1CR2CR3CR" ; "4CR5CR6CR")), CR))
TRANSPOSE(SPLIT("1CR2CR3CR4CR5CR6CR", "CR"))
TRANSPOSE({"1","2","3","4","5","6"})

finally:

1
2
3
4
5
6