app.py

@bot.command(name='play_song', help='To play song')
async def play(ctx,url):
    try :
        server = ctx.message.guild
        voice_channel = server.voice_client

        async with ctx.typing():
            filename = await YTDLSource.from_url(url, loop=bot.loop)
            voice_channel.play(discord.FFmpegPCMAudio(executable="ffmpeg.exe", source=filename))
        await ctx.send('**Now playing:** {}'.format(filename))
    except:
        await ctx.send("The bot is not connected to a voice channel.")


@bot.command(name='pause', help='This command pauses the song')
async def pause(ctx):
    voice_client = ctx.message.guild.voice_client
    if voice_client.is_playing():
        await voice_client.pause()
    else:
        await ctx.send("The bot is not playing anything at the moment.")
    
@bot.command(name='resume', help='Resumes the song')
async def resume(ctx):
    voice_client = ctx.message.guild.voice_client
    if voice_client.is_paused():
        await voice_client.resume()
    else:
        await ctx.send("The bot was not playing anything before this. Use play_song command")

@bot.command(name='stop', help='Stops the song')
async def stop(ctx):
    voice_client = ctx.message.guild.voice_client
    if voice_client.is_playing():
        await voice_client.stop()
    else:
        await ctx.send("The bot is not playing anything at the moment.")