How to print something without a new line in ruby

Use print instead. You may want to follow it up by STDOUT.flush.

$stdout.sync = true

100.times do
    print "."
    sleep 1
end

"How can I use “puts” to the console without a line break in ruby on rails?"

Also, you'll need to append "\r" at end of line to indicate "carriage return" and do next print at beginning of current line